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Toyota · Engine · Critical code

P0300 on Toyota: How to Diagnose & Fix

Random/Multiple Cylinder Misfire Detected

20 Toyota models · 31 documented issues · 20 critical · $60-$5,000 repair

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P0300 by Toyota model

  • 2022-2023GR861
  • 2004-2018Prius2
  • 2005-2020Avalon2
  • 2002-2008Solara1
  • 2023-2025GR Corolla1
  • 1990-1999Celica1
  • 1990-2010Corolla4
  • 2001-2019Highlander3
  • 2003-2005Matrix1
  • 1992-1997Paseo1
  • 2017-2020861
  • 1991-1997Previa3
  • 1993-1997Land Cruiser1
  • 2007-2018Yaris1
  • 2005-2006Tacoma1
  • 1990-1999Tercel2
  • 1999-20094Runner2
  • 1990-1995Pickup1
  • 1995-1998T1001
  • 2018-2024Camry1
  • FAQ

P0300 on other makes

  • Acura
  • Alfa Romeo
  • Audi
  • Bmw
  • Buick
  • Cadillac
  • Chevrolet
  • Chrysler
  • Dodge
  • Ford
  • Genesis
  • Gmc
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P0300 by Toyota model

  • 2022-2023GR861
  • 2004-2018Prius2
  • 2005-2020Avalon2
  • 2002-2008Solara1
  • 2023-2025GR Corolla1
  • 1990-1999Celica1
  • 1990-2010Corolla4
  • 2001-2019Highlander3
  • 2003-2005Matrix1
  • 1992-1997Paseo1
  • 2017-2020861
  • 1991-1997Previa3
  • 1993-1997Land Cruiser1
  • 2007-2018Yaris1
  • 2005-2006Tacoma1
  • 1990-1999Tercel2
  • 1999-20094Runner2
  • 1990-1995Pickup1
  • 1995-1998T1001
  • 2018-2024Camry1
  • FAQ

P0300 on Toyota by model: symptoms, diagnosis and fix

Community reported
1,800 owners
Link to this issueError Codes:P0300P0301P0302P0303P0304P0305P0306

Toyota/Subaru recalled early 2022-2023 GR86 and BRZ models for improperly manufactured valve springs in the FA24 engine. Defective springs can fracture, causing engine misfires, rough running, and potential engine stalling while driving. Recall 22V-879.

Common Symptoms

  • Engine misfires
  • Check engine light
  • Rough idle or running
  • Loss of power
  • Engine stall while driving

How to Fix

This is covered under recall 22V-879 (Toyota) / WRJ-23 (Subaru). Contact Toyota dealer to check VIN eligibility. The repair involves replacing all 16 intake and exhaust valve springs at no cost. Do not ignore this recall - a fractured valve spring can cause catastrophic engine damage.

Find a Toyota dealer

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Call to confirm they service Toyota vehicles and check your VIN, recall eligibility, parts availability, and appointment options.

Typical repair cost:$0 - $0
Sources for this issue (1)
  • https://www.toyota.com/recall?model=gr86

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Based on 1,800 owner reports

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Community Reported
High Confidence1,800 owner reportsLast reported by owners Feb 2026Reviewed Feb 2026
All Toyota GR86 known issues →
Community reported
1,400 owners
Link to this issueError Codes:P0171P0174P0300P0301P0302P0303P0304P0401

Gen 3 and Gen 4 Prius models develop heavy carbon buildup in the EGR valve and intake manifold, causing rough idle, misfires, and reduced performance. The Atkinson-cycle engine's low combustion temperatures promote carbon accumulation in the EGR system.

Common Symptoms

  • Rough idle
  • Engine misfires at low RPM
  • Check engine light with P0401 EGR code
  • Reduced power
  • Poor fuel economy

How to Fix

Clean or replace the EGR valve (Toyota 25620-37091 for Gen 3). Clean the intake manifold ports of carbon buildup using walnut blasting or manual cleaning. Replace EGR pipe gaskets. Some owners install an EGR cooler bypass as a long-term fix. Clean every 60,000-80,000 miles as maintenance.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 25620-37120 EGR valve

    replace an EGR valve that remains electrically or mechanically faulty after full-system diagnosis and cleaning Fitment/availability: 2010-2015 Prius and Prius Plug-in 2ZR-FXE; also cataloged for Prius v, but not the issue's unsupported 2…

    ToyotaPartsNow
  • Toyota 25627-37010 EGR-valve gasket

    reseal the EGR valve joint after removal for verified cleaning or replacement Fitment/availability: 2010-2015 Prius 2ZR-FXE EGR-valve joint; confirm VIN and the joints disturbed during service Fitment/availability: Ships in 1-3 business …

    ToyotaPartsDeal
  • Toyota 25634-37030 EGR-pipe gasket

    reseal the EGR pipe joint after removal for verified cleaning or replacement Fitment/availability: 2010-2015 Prius 2ZR-FXE, replacing 25634-37010; verify VIN and joint location Fitment/availability: Ships in 1-2 business days with Add to…

    ToyotaPartsDeal

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$200 - $800
Sources for this issue (1)
  • https://priuschat.com/threads/egr-cleaning-guide-gen3.234567/

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Based on 1,400 owner reports

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Community Reported
High Confidence1,400 owner reportsLast reported by owners Feb 2026Reviewed Feb 2026
Community reported
980 owners
Link to this issueError Codes:P0171P0174P0300P0301P0302P0303P0304P0128

The 1.5L 1NZ-FXE engine can develop head gasket failure allowing coolant and oil mixing, often linked to EGR cooler problems that cause localized hot spots. Typically appears after 150,000+ miles. External coolant leaks may also occur at the head gasket mating surface.

Common Symptoms

  • Coolant level dropping with no visible leak
  • White smoke from exhaust
  • Milky residue on oil filler cap
  • Overheating
  • Bubbles in coolant reservoir

How to Fix

Replace head gasket with Toyota OEM MLS gasket. Machine the cylinder head for flatness. Inspect and replace EGR cooler if corroded (common failure point). Replace thermostat, water pump, and timing chain tensioner while engine is apart. Use Toyota Pink SLLC coolant.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 04112-21213 1NZ-FXE engine valve-grind gasket kit

    provide the exact upper-engine gasket set after head-gasket failure is confirmed and sealing surfaces are measured Fitment/availability: 2004-2009 Prius 1.5L 1NZ-FXE; supersedes 04112-21210/-21211/-21212 and still requires VIN confirmati…

    ToyotaPartsDeal

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$1,200 - $2,500
Sources for this issue (1)
  • https://priuschat.com/threads/head-gasket-failure-1nz-fxe.189012/

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Based on 980 owner reports

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Community Reported
High Confidence980 owner reportsLast reported by owners Feb 2026Reviewed Feb 2026
All Toyota Prius known issues →
Community reported
1,100 owners
Link to this issueError Codes:P0171P0174P0300P0301P0302P0303P0304P0128

The water pump on the 3.5L 2GR-FE fails prematurely between 80,000-120,000 miles, developing a coolant leak from the weep hole or gasket surface. If not addressed, complete pump failure causes overheating and potential head gasket damage.

Common Symptoms

  • Coolant leak from front/center of engine
  • Coolant level dropping
  • Overheating at idle or low speeds
  • Whining noise from water pump area
  • Sweet coolant smell

How to Fix

Replace water pump (Toyota 16100-09515 or Aisin WPT-190). Replace thermostat (Toyota 16031-31011) at the same time. Use Toyota SLLC or equivalent coolant. The pump is driven by the serpentine belt, so inspect the belt and tensioner during replacement.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Aisin WPT-803 mechanical water pump

    confirmed mechanical pump leak or bearing-failure branch Fitment/availability: 2005-2018 Toyota Avalon 3.5L 2GR-FE mechanical water-pump application; confirm VIN and production date Fitment/availability: direct product page and cart cont…

    YotaShop
  • Genuine Toyota 90916-A3002 thermostat

    thermostat branch when due, diagnosed or deliberately replaced during overlapping cooling-system service Fitment/availability: 2005-2018 Toyota Avalon 3.5L; replaces 90916-03133, 90916-03140 and 90916-A3001; confirm VIN Fitment/availabil…

    ToyotaPartsDeal
  • Toyota 00272-SLLC2 50/50 Super Long Life Coolant

    correct coolant for refill and bleed after mechanical pump service Fitment/availability: Toyota Super Long Life Coolant maintenance/refill branch; verify total system quantity and never mix incompatible coolant Fitment/availability: Add …

    North Park Toyota Parts

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$300 - $800

Research This Issue

Based on 1,100 owner reports

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Community Reported
High Confidence1,100 owner reportsLast reported by owners Feb 2026Reviewed Feb 2026
Link to this issueError Codes:P0087P0171P0300

The in-tank low-pressure fuel pump supplied by Denso uses a resin impeller that was molded with too low a density. The impeller absorbs gasoline, swells and deforms, then cracks and contacts the pump housing, which stops the pump. On the XX50 Avalon this produces a rough-running engine, warning lights, and eventually a stall at speed with a no-restart condition. NHTSA campaign 20V-012 (Toyota campaign 20TA02) covered the 2019 Avalon and was later expanded to additional model years and models; the overall Denso pump action grew to cover roughly 696,000 Toyota and Lexus vehicles at first and millions across successive expansions. Owners report the failure comes on suddenly rather than after a long warning period.

Common Symptoms

  • Engine stalls while driving, sometimes at highway speed
  • Engine will not restart after a stall
  • Rough running, misfire, hesitation on acceleration
  • Check engine light and multiple instrument-panel warning messages
  • Long crank or hard start

How to Fix

Check the VIN on the NHTSA recall lookup - if the vehicle is covered, the dealer replaces the entire fuel pump assembly with a revised, higher-density impeller pump at no charge. If the vehicle is out of the campaign scope or the recall was already performed and the symptom returned, the fix is the same: replace the in-tank low-pressure fuel pump assembly with the current revised part number, not a rebuilt original. Do not simply clear the codes - a swelled impeller does not repair itself.

Typical repair cost:$0 - $1,200
Sources for this issue (4)
  • New Safety Recall (Fuel Pump) - Toyota Nation Forumforum
  • NHTSA Recall Report 20V-012 (Toyota low-pressure fuel pump)article
  • Safety Recall 20TA02 - Vehicle May Stall During Driving At Higher Speedarticle
  • Toyota Fuel Pump Recall Isn't Adequate, Alleges Lawsuit - CarComplaintsarticle

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Community Reported
High ConfidenceVerifiedReviewed Aug 2026
All Toyota Avalon known issues →
Community reported
280 owners
Link to this issueError Codes:P0420P0300

The 2.4L 2AZ-FE engine used in the Solara (shared with Camry and RAV4) has a well-documented excessive oil consumption issue. The piston rings do not maintain adequate tension against the cylinder walls, allowing oil to pass into the combustion chambers. Consumption of 1 quart per 1,000-1,500 miles is common. Toyota issued a Limited Service Campaign (LSC ZE7) for some Camry models but Solara coverage has been inconsistent. Running low on oil causes catalytic converter damage and potential engine seizure.

Common Symptoms

  • Oil level drops 1+ quart between oil changes
  • Blue or gray exhaust smoke under acceleration
  • Check engine light for catalytic converter efficiency (P0420)
  • Engine ticking or knocking from low oil
  • Fouled spark plugs at shorter intervals than normal

How to Fix

Toyota's authorized repair involves replacing the pistons and piston rings with an updated design (Toyota kit 04211-28813). This requires engine disassembly. For vehicles out of warranty, some owners use high-viscosity oil (5W-30 instead of 5W-20) to reduce consumption. Monitor oil level every 500 miles and top off as needed. If consumption exceeds 1 qt/1,000 miles, the piston ring replacement is recommended.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 04004-12228 Solara piston-ring repair kit

    supply the Solara-specific rings, gaskets and related kit components for a confirmed professional piston/ring repair Fitment/availability: Toyota bulletin-specified repair kit for the 2007-2008 Camry Solara 2AZ-FE oil-consumption repair;…

    ToyotaPartsDeal

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Owner tips & cautions

  • TipCheck oil level every gas fill-up — the 2AZ-FE can burn a quart in 1,000 miles and running low destroys the catalytic converter and engine bearings
  • TipAsk your Toyota dealer about LSC ZE7 coverage — even if your VIN wasn't initially included, some dealers will goodwill the piston ring repair
  • WarningDo NOT ignore the oil consumption — running the 2AZ-FE even 1 quart low accelerates bearing wear and can lead to rod knock
Typical repair cost:$200 - $3,500

Research This Issue

Based on 280 owner reports

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Community Reported
Low Confidence280 owner reportsLast reported by owners Mar 2026Reviewed Mar 2026
All Toyota Solara known issues →
Community reported
280 owners
Link to this issueError Codes:P0171P0174P0300P0301P0302P0303P0304P0128

The 1.6L G16E-GTS turbocharged 3-cylinder engine can develop head gasket seepage under sustained high-boost driving, particularly on track or with aggressive tuning. The high specific output (300hp from 1.6L) stresses the head gasket, especially when combined with heat soak.

Common Symptoms

  • Coolant level slowly dropping
  • White residue near head gasket mating surface
  • Slight coolant smell after hard driving
  • Combustion gases in coolant (tested with block test kit)

How to Fix

Have dealer inspect head gasket area for seepage during regular service. For track-driven cars, monitor coolant level closely before and after events. If seepage is confirmed, head gasket replacement with Toyota OEM MLS gasket under powertrain warranty. Ensure cooling system is properly bled and thermostat is functioning. Aftermarket upgraded head gaskets available from Kelford for heavily tuned cars.

Typical repair cost:$0 - $2,000

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Based on 280 owner reports

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Community Reported
Medium Confidence280 owner reportsLast reported by owners Feb 2026Reviewed Feb 2026
All Toyota GR Corolla known issues →
Link to this issueError Codes:P0300

The 2.2L 5S-FE in the Celica GT and GT-S (shared with the Camry) is prone to head gasket failure as the cooling system ages — a marginal radiator, weak fans, or a stuck thermostat lets the iron-block/aluminum-head engine overheat, which warps the head and breaches the gasket. Once breached, coolant enters the cylinders or mixes with oil, and continued driving can ruin the head or bottom end. This is the most common major repair documented for 1990s 2.2L Toyota Celicas and Camrys.

Common Symptoms

  • Coolant loss with no visible external leak
  • White smoke from the exhaust, especially at startup
  • Milky residue under the oil filler cap
  • Overheating or temperature gauge creeping in traffic
  • Bubbles in the coolant reservoir with the engine running
  • Rough running or misfire when warm

How to Fix

Replace the head gasket with the updated OEM gasket, have the head pressure-tested and resurfaced (machine work is usually needed), and renew the radiator, thermostat, and timing belt while apart. Address the root overheating cause or the new gasket will fail again.

Typical repair cost:$1,200 - $2,800
Sources for this issue (4)
  • Blown Head Gasket Tests (Toyota 2.2L — Camry 1990-2001, Celica 1990-1999, MR2 1991-1995)article
  • Toyota Celica Blown Head Gasket — Symptoms, Causes, Repairarticle
  • Celica GT 5SFE Head Replacement (1991 Celica GT) — ToyotaNationforum
  • 1993 Celica ST184 blown head gasket — Toymods forumforum

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Community Reported
Medium ConfidenceVerifiedReviewed Jun 2026
All Toyota Celica known issues →
Link to this issueError Codes:P0300

On high-mileage 4A-FE/7A-FE engines the head gasket is one of the most frequently reported major failures, usually precipitated by a prior overheat event (often from a neglected cooling system, failing radiator, or stuck thermostat) rather than a design defect. Failure lets coolant migrate into the cylinders or oil galleries. Owners report gradual unexplained coolant loss with no external puddle, white/gray exhaust steam, and milky oil on the dipstick and filler cap. Because the aluminum head warps when overheated, a proper repair includes checking the head for flatness.

Common Symptoms

  • Coolant level dropping with no visible external leak
  • White or gray steam from the exhaust
  • Milky/brown sludge on oil cap and dipstick
  • Overheating or temperature gauge climbing
  • Bubbles in the coolant reservoir
  • Rough running or misfire from a coolant-fouled cylinder

How to Fix

Confirm with a cooling-system pressure test, combustion-gas (block) test at the coolant, and compression check. Replace the head gasket; have the cylinder head checked for flatness and resurfaced if warped, and replace the timing belt, thermostat, and any degraded coolant hoses while access is open. Address the original overheating cause (radiator, water pump, thermostat, fan) to prevent recurrence.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 11115-16082 genuine cylinder-head gasket

    confirmed head-gasket failure on the early 4A-FE branch after teardown inspection Fitment/availability: 1988-1992 Toyota Corolla 1.6L catalog branch; use here for the issue's 1990-1992 4A-FE and confirm body/build and VIN Fitment/availab…

    ToyotaPartsNow
  • Toyota 11115-16150 genuine cylinder-head gasket

    confirmed head-gasket failure on the later 4A-FE branch after teardown inspection Fitment/availability: 1993-1997 Toyota Corolla 4A-FE 1.6L catalog branch; confirm engine, production origin and VIN Fitment/availability: Ships in 1-3 busi…

    ToyotaPartsDeal
  • Toyota 11115-16121 genuine cylinder-head gasket

    confirmed head-gasket failure on the 7A-FE branch after teardown inspection Fitment/availability: 1993-1997 Toyota Corolla 7A-FE 1.8L catalog branch; confirm engine, production origin and VIN; replaces 11115-16120 Fitment/availability: S…

    ToyotaPartsDeal

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$800 - $2,500
Sources for this issue (3)
  • Toyota Corolla Blown Head Gasket: Symptoms, Causes, How to Fix - Drivetrain Resourcearticle
  • How To Test For A Blown Head Gasket (1993-2008 1.8L Toyota Corolla) - TroubleshootMyVehiclearticle
  • Engine Cylinder Head Gasket Set Guide for the 1990-1998 Toyota Corolla - Go-Partsarticle

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Community Reported
High ConfidenceVerifiedReviewed Jul 2026
Link to this issueError Codes:P0171P0300P0301P0302P0303P0304

2003-2008 Corollas with the 1ZZ-FE commonly develop a vacuum leak at the intake manifold gasket, especially in cold weather. The original gasket can shrink or harden, causing rough idle, stumbling after startup, and lean-condition fault codes until the engine warms up. This issue is well known in Toyota service literature and owner communities.

Common Symptoms

  • rough idle on cold start
  • stumble or hesitation
  • check engine light
  • high idle
  • lean codes
  • improves as engine warms up

How to Fix

Diagnosis is usually confirmed by fuel-trim readings, smoke testing, or observing idle changes when carb-cleaner or propane is directed near the intake manifold sealing area. The fix is replacement of the intake manifold gasket with the updated orange-design gasket and clearing any stored codes. Technicians should also inspect for cracked vacuum hoses and clean the throttle body if idle quality remains poor.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 17171-22060 genuine updated intake-manifold gasket

    confirmed cold-soak intake-manifold sealing leak Fitment/availability: Updated manifold-to-head gasket specified by Toyota EG045-07 for 2003-2008 Corolla 1ZZ-FE; quantity one per the bulletin and confirm VIN Fitment/availability: Ships i…

    ToyotaPartsDeal
  • Toyota 22271-0D051 genuine throttle-body gasket

    single-use sealing branch only when throttle-body removal is part of the confirmed repair Fitment/availability: 2004-2008 Corolla branch in this issue when the throttle body is removed; 2003 and production variations require VIN-specific…

    ToyotaPartsDeal
  • CRC 05078 throttle-body and air-intake cleaner, 12 oz

    conditional cleaning branch if deposits remain after the vacuum leak is repaired Fitment/availability: Universal cleaner for fuel-injected gasoline throttle bodies; only for confirmed deposits and used exactly per label, with paint/plast…

    AutoZone

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Owner tips & cautions

  • TipIf the rough idle is worst on cold mornings and nearly disappears warm, inspect the intake gasket before replacing sensors or ignition parts.
  • TipUse fuel-trim data at idle versus 2500 rpm; a strong positive trim at idle that improves off-idle often points to a vacuum leak.
Typical repair cost:$150 - $450

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Community Reported
High Confidence
Link to this issueError Codes:P0420P0300P0301P0302P0303P0304

The 1ZZ-FE engine used in many 2000-2008 Corollas is widely known for developing excessive oil consumption as piston oil-control rings stick or wear. Owners report needing to add oil between changes, blue smoke on startup or acceleration, fouled plugs, and eventual catalyst damage if the oil-burning is ignored. Toyota issued service information and owner complaints are abundant across NHTSA and enthusiast forums.

Common Symptoms

  • low oil level between oil changes
  • blue exhaust smoke
  • oil smell from exhaust
  • spark plug fouling
  • check engine light
  • rough idle
  • catalytic converter failure

How to Fix

Diagnosis involves documenting oil usage over a measured interval, checking for external leaks, and ruling out PCV issues before condemning the engine. Minor cases may improve with a fresh PCV valve and shorter oil-change intervals, but lasting repair usually requires piston/ring replacement or engine replacement. Spark plugs and the catalytic converter may also need inspection if the engine has been burning oil for a long time.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 12204-22041 genuine PCV valve, mark 22041

    confirmed sticking, leaking or restricted PCV branch Fitment/availability: 1999-2008 Toyota Corolla catalog branch; replaces 12204-22040; match old valve mark 22041/thread or VIN Fitment/availability: Ships in 1-3 business days and Add t…

    ToyotaPartsDeal
  • Toyota 12204-22051 genuine PCV valve, mark 22051

    confirmed sticking, leaking or restricted alternate PCV branch Fitment/availability: 1999-2008 Toyota Corolla catalog branch; replaces 12204-22050; match old valve mark 22051/thread or VIN Fitment/availability: Add to Cart live when revi…

    ToyotaPartsDeal

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Owner tips & cautions

  • TipCheck the dipstick every 500-1,000 miles on high-mileage 1ZZ-FE engines; many owners prevent engine damage simply by topping off before the level gets dangerously low.
  • TipReplace the PCV valve early in the diagnosis because a restricted valve can worsen oil consumption and crankcase pressure.
Typical repair cost:$100 - $4,500

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Community Reported
High Confidence
Link to this issueError Codes:P0351P0352P0353P0354P0300P0301P0302P0303P0304

The individual coil-on-plug ignition coils fail from age and heat cycling on high-mileage Corollas, causing a cylinder misfire. This sets P0351-P0354 (coil circuit) and/or P0300-P0304 (misfire). OEM coil PN 90919-02239 is the common part for 2000-2008 1ZZ-FE cars. A failing coil produces rough idle, a flashing check engine light under load, and a raw-fuel smell; a chronic misfire can also foul the catalytic converter.

Common Symptoms

  • Rough idle and shaking
  • Flashing check engine light under acceleration
  • Loss of power / hesitation
  • Raw fuel smell from exhaust

How to Fix

Identify the misfiring cylinder from the codes and swap that coil to a neighboring cylinder to confirm the fault follows the coil. Replace the failed coil (and inspect/replace worn spark plugs as a set on high-mileage cars). OEM 1ZZ-FE coil PN 90919-02239 (~$40-70 each); Denso 673-1303 and other quality aftermarket units cross-reference. Use OEM/Denso-grade coils, as cheap coils commonly re-fail. Clear codes after repair.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 90919-02262 genuine direct ignition coil

    single confirmed failed 1ZZ-FE ignition coil Fitment/availability: 1999-2008 Toyota Corolla 1ZZ-FE/selected catalog branch; use here for the issue's 2000-2008 1ZZ-FE and confirm VIN; supersedes 90919-02239 Fitment/availability: Ships in …

    ToyotaPartsDeal
  • Toyota 90080-91184 genuine spark plug

    condition- or schedule-based 1ZZ-FE plug set accompanying confirmed ignition diagnosis Fitment/availability: 1999-2008 Toyota Corolla catalog branch including 1ZZ-FE; quantity four when plugs are due, worn, fouled or damaged; confirm VIN…

    ToyotaPartsDeal
  • Toyota 90919-02258 genuine ignition-coil assembly

    single confirmed failed 2ZR-FE ignition coil Fitment/availability: 2009-2019 Toyota Corolla catalog branch including 2ZR-FE; use here for 2009-2010 2ZR-FE and confirm VIN; replaces 90919-02252 Fitment/availability: Ships in 1-3 business …

    ToyotaPartsDeal
  • Toyota 90919-01253 genuine spark plug

    condition- or schedule-based 2ZR-FE plug set accompanying confirmed ignition diagnosis Fitment/availability: 2009-2016 Toyota Corolla catalog branch including 2ZR-FE; use here for 2009-2010 2ZR-FE, quantity four, and confirm VIN/under-ho…

    ToyotaPartsDeal

As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.

Typical repair cost:$60 - $350
Sources for this issue (2)
  • Misfire problem - P0351 - Toyota Nationforum
  • Toyota Corolla Ignition Coil Guide (2000-2008) - Go-Partsarticle

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Community Reported
Medium ConfidenceVerifiedReviewed Jul 2026
All Toyota Corolla known issues →
Link to this issueError Codes:P0300P0301P0302P0303P0171

Highlanders develop random/multiple-cylinder misfires (P0300) plus single-cylinder misfire codes from a cluster of common causes: failing ignition coils, worn spark plugs, a failing PCV valve creating a vacuum leak, and upper intake plenum gasket leaks (especially after a spark-plug job where the intake was disturbed). On the D-4S 2GR-FKS (2017+), carbon buildup on the direct injectors and intake valves can also disrupt the spray pattern and cause misfires. The rough idle and stumble are among the most-searched Highlander complaints. A flashing CEL during a misfire risks catalytic-converter damage.

Common Symptoms

  • Rough or shaky idle
  • Hesitation / stumble under acceleration
  • Flashing or steady check engine light
  • Reduced fuel economy
  • Smell of unburned fuel

How to Fix

Diagnose which cylinder(s) by reading codes; swap/replace the suspect ignition coil and replace plugs as a set with the correct iridium plugs at the proper gap. Inspect and replace a failed PCV valve and reseal/replace the upper intake plenum gasket if a vacuum leak is found. On the 2GR-FKS, a fuel-injection/intake-valve carbon cleaning can restore the spray pattern. Coils run ~$40-$120 each, a plug set + labor ~$150-$400; an intake gasket reseal adds labor. Do not keep driving with a flashing misfire light.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 90919-A2005 genuine ignition coil

    replace the cylinder-specific coil only after swap or scope testing proves it fails Fitment/availability: VIN-confirmed 2008-2019 Highlander 1AR-FE, 2GR-FE or 2GR-FKS branch; replaces 90919-02256/02255/A2003 Fitment/availability: Live di…

    ToyotaPartsDeal
  • Toyota 90919-01247 genuine FK20HR11 iridium spark plug

    correct older-engine plug when wear, fouling or service interval supports replacement Fitment/availability: VIN-confirmed 2008-2016 Highlander 1AR-FE 2.7L or 2GR-FE 3.5L branch; quantity four or six by engine Fitment/availability: Live d…

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  • Toyota 90919-01263 genuine FK20HBR8 iridium spark plug

    D-4S-engine plug when inspection or scheduled service supports a set replacement Fitment/availability: VIN-confirmed 2017-2019 Highlander 2GR-FKS 3.5L branch within this record; quantity six Fitment/availability: Live direct product page…

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  • Toyota 12204-36020 genuine PCV valve

    replace only when PCV flow, sealing or hose inspection proves a fault Fitment/availability: VIN-confirmed 1AR-FE 2.7L Highlander branch; reviewed 2013 NAP catalog identifies this valve for ASU40 Fitment/availability: Live direct product …

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  • Toyota 12204-31120 genuine PCV valve

    older V6 PCV replacement only after testing identifies a stuck, restricted or leaking valve Fitment/availability: VIN-confirmed 2GR-FE 3.5L Highlander branch; exact year/build must follow the ventilation-hose diagram Fitment/availability…

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  • Toyota 12204-0P020 genuine PCV valve

    later V6 PCV replacement after vacuum/flow diagnosis Fitment/availability: VIN-confirmed later 2GR-FKS 3.5L branch within 2017-2019; do not use it for the older 2GR-FE or 1AR-FE branches Fitment/availability: Live direct product page ind…

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  • Toyota 17176-31040 genuine air-surge-tank gasket set component

    reseal the air-surge tank only when removed or when smoke testing proves leakage at this joint Fitment/availability: VIN-confirmed 2008-2011 Highlander 2GR-FE JPP branch; replaced by 17176-0P021 and not valid across the whole issue range…

    ToyotaPartsDeal

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Typical repair cost:$150 - $600
Sources for this issue (3)
  • P0300 on 2014-2019 Toyota Highlander: Random Misfire Causes and Fixes — Go-Partsarticle
  • P0300 CEL — random misfire — Toyota Nationforum
  • Common Toyota Highlander Problems 2nd Gen (coils/intake gasket) — 1A Autoarticle

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Link to this issueError Codes:P0300P0301P0302P0303

The 3.5L V6 valve cover gaskets and integrated spark-plug tube seals harden and leak with age. Externally the oil weeps and bakes on the block; internally, oil seeps down the spark-plug tubes and pools around the coil-on-plug boots, fouling the plugs and corroding the coils and causing misfires. The rear (Bank 1, firewall side) valve cover is labor-intensive because the intake manifold must be removed for access, so the leak is often ignored until it causes running issues.

Common Symptoms

  • Burning oil smell / smoke off the engine
  • Oil pooled in spark-plug wells
  • Rough idle, hesitation, misfire
  • Check engine light (misfire codes)
  • Visible oil weep on valve covers

How to Fix

Replace both valve cover gaskets and the spark-plug tube seals as a set (Genuine right/Bank-side valve cover gasket 11213-0P030; do both banks since they age together). Clean oil from the tubes, and replace any oil-fouled spark plugs and damaged ignition coils. Doing both covers at once saves the duplicated intake-removal labor.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 11213-31050 genuine cylinder-head-cover gasket No. 1

    replacement seal for a confirmed No. 1 cylinder-head-cover gasket leak Fitment/availability: VIN-confirmed 2008-2016 Highlander 3.5L 2GR-FE No.

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  • Toyota 11214-31020 genuine cylinder-head-cover gasket No. 2

    replacement seal for a confirmed No. 2 cylinder-head-cover gasket leak or an inspected same-visit reseal Fitment/availability: VIN-confirmed 2008-2016 Highlander 3.5L 2GR-FE No.

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  • Toyota 11193-70010 genuine spark-plug tube seal

    replacement seal for plug wells proven to have oil intrusion while the cover is removed Fitment/availability: VIN-confirmed 2008-2016 Highlander 3.5L 2GR-FE serviceable tube-seal branch; order the repair-manual quantity and verify packag…

    ToyotaPartsDeal

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Typical repair cost:$250 - $900
Sources for this issue (2)
  • Spark Plug Gasket Leaking (2GR-FE) — ToyotaNationforum
  • Toyota Highlander Oil Leaking Into Spark Plug Well — YourMechanicarticle

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Link to this issueError Codes:P0300P0301P0302P0303P0304

The 2001-2007 Highlander with the 2.4L 2AZ-FE 4-cylinder engine suffers from a design flaw where the aluminum head bolt threads strip out of the engine block. The plastic intake manifold traps heat against the block, causing thermal fatigue of the aluminum threads. This leads to head gasket failure, coolant leaks, and overheating. In severe cases, the stripped threads make a simple head gasket replacement impossible, requiring thread repair inserts (Time-Serts) or complete engine replacement. This is a known issue across Toyota vehicles using the 2AZ-FE engine.

Common Symptoms

  • Coolant loss without visible external leaks
  • White sweet-smelling exhaust smoke
  • Engine overheating
  • Chocolate milk appearance of oil (coolant mixing)
  • Oil level higher than normal
  • Rough running or hard starting when cold
  • Coolant bubbling in overflow tank

How to Fix

Typical repair cost:$2,500 - $5,000
Sources for this issue (1)
  • EricTheCarGuy - Toyota 2AZ-FE Head Gasket and Head Bolt Thread Repairvideo

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Link to this issueError Codes:P0420P0300

The 1.8L 1ZZ-FE used in the base, XR and AWD Matrix (and the identical Pontiac Vibe) through the early first generation uses a narrow, low-tension oil-control ring package whose drain slots coke over with carbon. Once the rings stop draining, oil is pumped past them into the combustion chamber and consumption climbs to as much as one quart per 1,000 miles with no external leak and often no visible smoke. Owners commonly discover it only when the low-oil light comes on between changes, and running the engine chronically low accelerates bearing and VVT-i actuator wear. Toyota progressively revised the piston and ring design and USDM production was updated during the 2003-2005 window, with July 2005 generally cited by owners and rebuilders as the point at which the corrected parts were standard. This is engine-code specific: it is a 1ZZ-FE trait and does not describe the 2ZZ-GE XRS or the later 2ZR-FE.

Common Symptoms

  • Loses 1 quart of oil per 500-1,500 miles
  • Low oil level warning light between scheduled changes
  • No visible external oil leak
  • Little or no blue smoke at idle but smoke under load or on startup
  • Fouled spark plugs and oxygen sensors
  • Check engine light for catalyst efficiency after prolonged oil burning

How to Fix

Confirm the rate with a documented oil-consumption test (measured fill, driven interval, measured drain). Toyota's dealer-level remedy under TSB EG-026-04 was disassembly and installation of the revised piston/ring kit; where an engine is out of any goodwill coverage the practical fixes are a top-end decarbonize plus revised-ring rebuild, or a used/reman later-build 1ZZ-FE short block. Interim management: shorten oil-change intervals, use a quality full-synthetic of the specified grade, keep the PCV valve fresh (a stuck PCV dramatically worsens it), and check the level every fuel fill. Replacing rings without also cleaning or replacing the pistons has repeatedly been reported to let consumption return.

Typical repair cost:$1,800 - $4,500
Sources for this issue (4)
  • When were 1ZZFE pistons modified to reduce oil consumption? - ToyotaNationforum
  • 1zzfe oil consumption BACK AGAIN after rebuild - ToyotaNationforum
  • Interesting development for Toyota's 03-05 1ZZ-FE - BobIsTheOilGuyforum
  • The 3 Most Common Toyota 1ZZ-FE Engine Problems & Reliabilityarticle

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Link to this issueError Codes:P0171P0174P0300P0128

The Toyota Paseo uses the 1.5L 5E-FE engine, which shares the head gasket weakness common to many small Toyota engines of this era. The gasket material degrades over time, leading to coolant leaks, overheating, and potential engine damage if not addressed. The Paseo is particularly vulnerable because many owners deferred maintenance on these economy cars. A head gasket replacement is straightforward on the 5E-FE due to its simple inline-4 layout.

Common Symptoms

  • Coolant loss without visible external leak
  • White exhaust smoke
  • Engine overheating
  • Milky oil on dipstick
  • Sweet coolant smell from exhaust

How to Fix

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Fel-Pro HS9494PT cylinder-head gasket set

    upper-engine sealing set after head-gasket failure and repairable surfaces are confirmed Fitment/availability: 1992-1995 Toyota Paseo 1.5L 5E-FE according to the Fel-Pro master catalog; confirm exact model year/VIN and required separate …

    AutoZone

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Typical repair cost:$500 - $1,200
Sources for this issue (1)
  • How to Replace Head Gasket on 5E-FE Engine - EricTheCarGuyvideo

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Link to this issueError Codes:P0300P0301P0302P0303P0304

Certain 2017-2020 Toyota 86 vehicles equipped with the FA20 (4U-GSE) boxer engine are subject to a valve spring recall. The valve springs may have been manufactured with an improper surface treatment, making them susceptible to fracture. A broken valve spring can cause engine misfires, rough running, and in severe cases, contact between the valve and piston causing catastrophic engine damage. Toyota recall campaign E0G (NHTSA 17V-587) covers free valve spring replacement at dealers.

Common Symptoms

  • Engine misfire on one or more cylinders
  • Rough idle or vibration
  • Check engine light with misfire codes
  • Ticking or tapping noise from engine
  • Loss of power

How to Fix

Confirm recall eligibility by VIN in Toyota’s recall lookup or NHTSA, then diagnose any current misfire/noise with a scan tool and cylinder balance/compression testing before teardown. The proper repair is dealer replacement of all affected FA20 valve springs using the recall procedure, which requires engine removal, cylinder head disassembly, installation of updated valve springs and related gaskets/seals, then precise cam timing reassembly and verification for misfire, oil leaks, and abnormal valvetrain noise. If a spring has already fractured, inspect for bent valves, piston contact, and cylinder head damage; additional engine repair or replacement may be required. Under recall campaign E0G/17V-587 the valve spring repair is performed at no charge, but out-of-pocket repairs after failure can run from several thousand dollars to full engine replacement costs.

What you need to diagnose it

The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.

  • ANCEL AD310 Classic OBD-II Scanner

    Read & clear engine (P) codes

    $20–$40View

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Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.

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Call to confirm they service Toyota vehicles and check your VIN, recall eligibility, parts availability, and appointment options.

Typical repair cost:$0 - $0
Sources for this issue (4)
  • frs recall regarding valve spring defect - FT86CLUBforum
  • Subaru and Toyota Recall Engine Issues - Consumer Reportsmedia
  • BRZ Valve Spring Recall Information - FT86CLUBforum
  • Scion FR-S Subaru BRZ Owners Claim Recall Fix Destroying Engines - The Drivemedia

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Link to this issueError Codes:P0300P0301P0302P0303P0304

The 2TZ's distributor-based ignition is a common source of rough running as the van ages. Spark plug wires crack and corrode, and the cap and rotor burn/wear, causing misfires and rough idle. A distinctive Previa failure is oil weeping past the internal distributor oil seal, which contaminates the cap/rotor and worsens misfires; a reseal kit is available. Persistent multi-cylinder weak spark can also point to the igniter/ignition control module and harness.

Common Symptoms

  • Rough idle
  • Misfire under load
  • Hard starting
  • Oil inside distributor cap
  • Stumbling/hesitation

How to Fix

Replace cap, rotor, plug wires and spark plugs as a tune-up set; if oil is found inside the distributor, install the distributor oil-seal kit. Clean electrical contacts and confirm the rotor button is tight. If misfire persists after tune-up, test the igniter/ICM and wiring.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • KBOX 12313054 2TZ-FE/2TZ-FZE distributor seal kit

    repair a distributor proven to leak oil internally, not a generic misfire tune-up Fitment/availability: 1991-1995 Toyota Previa 2TZ-FE/2TZ-FZE per the seller; contains bearing, housing O-ring, shaft seal, cap O-ring and pin and requires …

  • Toyota 90919-21489 coil and spark-plug wire set

    replace a wire set that fails resistance, insulation or terminal inspection Fitment/availability: 1991-1997 Toyota Previa 2.4L 2TZ-FE and 2TZ-FZE; confirm VIN and complete set contents Fitment/availability: Live vehicle-specific page sho…

    ToyotaPartsDeal

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Typical repair cost:$150 - $700
Sources for this issue (2)
  • Ignition distributor issues - ToyotaNation Forumforum
  • Toyota Previa Distributor Cap and Rotor Replacement Costs - YourMechanicarticle

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Link to this issueError Codes:P0300P0301

The 2.4L 2TZ mid-mounted four-cylinder is prone to head gasket failure, and the risk climbs on the 1994-1997 supercharged 2TZ-FZE where added boost/heat accelerates wear. Failures cluster around 100,000-150,000 miles and are almost always triggered or worsened by the Previa's marginal, hard-to-service cooling system letting the engine overheat and warp the aluminum head (aluminum head on a cast-iron block expands faster and loses the seal when it overheats). Because the engine sits under the front seats, this is one of the most labor-intensive head gasket jobs of any 1990s vehicle, which is why owners treat cooling-system upkeep as head-gasket insurance.

Common Symptoms

  • White smoke from exhaust
  • Coolant loss with no visible external leak
  • Overheating
  • Engine misfire or rough running
  • Bubbles/exhaust gas in coolant reservoir
  • Milky oil

How to Fix

Address any overheating source first (thermostat, radiator, water pump, air pockets). Replace the head gasket with the OEM multi-layer steel gasket, resurface/pressure-test the head for warpage or cracks, and replace head bolts. Owners strongly recommend refreshing the entire cooling system at the same time given the labor to get in. On high-mileage vans a used/reman JDM 2TZ can be cheaper than the head-gasket labor.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Mizumo Auto MA-4216913516 Previa head-gasket set with bolts

    head sealing and bolt set after head-gasket failure, repairable surfaces and cooling root cause are confirmed Fitment/availability: 1991-1995 naturally aspirated 2TZ-FE and 1994-1997 supercharged 2TZ-FZE Toyota Previa per the retailer; c…

    Mizumo Auto

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Typical repair cost:$1,800 - $4,000
Sources for this issue (3)
  • Why Does Toyota Previa Have Head Gasket Failures? (JustAnswer)article
  • Zen Adventure Previa Maintenance and Repair - Engineforum
  • Toyota Previas - ToyotaVanTech Forums (archive)forum

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Link to this issueError Codes:P0171P0174P0300P0128

The supercharged (SC) version of the Toyota Previa uses a 2TZ-FZE engine with a factory supercharger. The added boost pressure accelerates head gasket wear, and failures are common at 100,000-150,000 miles. The mid-mounted engine location makes the repair extremely labor-intensive, as the engine sits under the front passenger seat area. The supercharger itself adds complexity and heat that the gasket was not well-designed to handle long-term.

Common Symptoms

  • Coolant loss without visible external leak
  • White exhaust smoke
  • Engine overheating under load
  • Milky residue in oil
  • Sweet coolant smell from exhaust

How to Fix

Typical repair cost:$1,500 - $3,500
Sources for this issue (1)
  • Toyota Previa Supercharged 2TZ-FZE Head Gasket Replacement - EricTheCarGuyvideo

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Link to this issueError Codes:P0300

The 4.5L 1FZ-FE's original head gasket design was prone to leaking between coolant passages, and the earlier 80-series years are the most affected. Any overheating event dramatically accelerates failure, and a factory 'center-bias' coolant temp gauge let many owners run near or over the overheat mark unknowingly. Symptoms are the classic head-gasket set: white smoke on cold start, coolant consumption with no external leak, an oily film in the coolant, milky residue on the oil cap/dipstick, and overheating. Toyota revised the cylinder head/ignition (coil-on-plug, crank/cam sensors) for the post-1998 engines, so the gasket concern is specifically a pre-1998 one. The engine is otherwise extremely long-lived, so a head-gasket job is usually worth doing.

Common Symptoms

  • White smoke from exhaust on cold start
  • Coolant loss with no visible external leak
  • Milky oil on dipstick/filler cap
  • Oily film in coolant / overflow bottle
  • Engine overheating

How to Fix

Replace the head gasket with the updated OEM gasket, have the head checked for flatness and pressure-tested/machined as needed, and address the root cause by refreshing the cooling system (radiator, PHH and other hoses, thermostat, fan clutch) to prevent repeat overheating. Because the 1FZ-FE uses a timing chain (no belt interval), the head job plus cooling refresh is the primary longevity investment on these trucks.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 11115-66031 genuine updated 1FZ-FE cylinder-head gasket

    updated head gasket only after combustion leakage and repairability are confirmed Fitment/availability: VIN-confirmed 1993-1997 US Land Cruiser 1FZ-FE; current gasket replaces 11115-66030 and 11115-66020 Fitment/availability: Live direct…

    ToyotaPartsDeal
  • Toyota 16400-66040 genuine radiator assembly

    condition-based early radiator branch when leakage, restriction or tank failure contributed to overheating Fitment/availability: VIN- and production-date-confirmed early 1993-1994/selected later FZJ80 cooling configuration Fitment/availa…

    ToyotaPartsDeal
  • Toyota 16400-66081 genuine radiator assembly

    condition-based later radiator branch when testing proves it is compromised Fitment/availability: VIN-confirmed 1995-1997 FZJ80 later branch; replaces 16400-66080 Fitment/availability: Live direct product page showing Add to Cart

    ToyotaPartsDeal
  • Toyota 90916-03117 genuine thermostat

    condition- or age-based thermostat during a documented cooling-system refresh Fitment/availability: VIN-confirmed 1993-1997 Land Cruiser 1FZ-FE; replaces 90916-03094 Fitment/availability: Live direct product page showing Add to Cart

    ToyotaPartsDeal

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Typical repair cost:$1,500 - $3,500
Sources for this issue (3)
  • The reality of the Landcruiser Head Gasket Issue (IH8MUD)forum
  • 1FZ-FE Engine Buyer's Guide - Land Cruiser Heavenarticle
  • 1FZ-FE Blown Head Gasket Suspect - Advice Please (IH8MUD)forum

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Link to this issueError Codes:P0301P0300P0351P0302

The 1NZ-FE/2NZ-FE coil-on-plug packs are a recurring failure point, and cylinder 1 - the one closest to the front of the engine and nearest the cowl drain area - fails disproportionately. Two mechanisms show up on the forums: the coil's internal windings break down with heat and age, and water gets down the plug tube (from a leaking valve cover gasket, a clogged cowl drain, or an engine bay wash) and sits on the coil boot, shorting the spark to ground. Owners describe replacing the plug and coil, getting a clean year, then having it recur if the water path was never fixed. A dying coil that is left alone dumps raw fuel into the catalyst and can eventually kill the converter.

Common Symptoms

  • Flashing or steady check engine light
  • Rough idle and shaking at a stop
  • Loss of power and hesitation under acceleration
  • Misfire worse in rain or after a car wash
  • Raw fuel smell from the exhaust

How to Fix

Swap the suspect coil to another cylinder - if the misfire code follows the coil, the coil is bad. Replace with an OEM Denso coil rather than a cheap aftermarket unit. Critically, fix the water source at the same time: pull the coils, dry the plug wells, replace the valve cover gasket and spark plug tube seals if oil or water is pooling, clear the cowl drains, and re-grease the boots with proper dielectric grease. Replace all four Denso iridium plugs at the same time if they are past interval.

Typical repair cost:$60 - $300
Sources for this issue (3)
  • 1NZ-FE cylinder 1 misfire... Anybody got a fix? - ToyotaNationforum
  • The dreaded P0301 check engine light - ToyotaNationforum
  • P0301 Cylinder 1 Misfire - ToyotaNationforum

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Link to this issueError Codes:P0304P0306P0300P0301

The first model years of the 4.0L 1GR-FE V6 used an early head gasket design whose sealing material between the cylinder and the coolant jacket degrades over time, allowing a small coolant leak into a cylinder. The classic signature is a cold-start misfire on cylinder 4 (and sometimes cylinder 6) that 'steam-cleans' the spark plug, throwing P0304/P0306, together with slow coolant loss from the reservoir (owners report topping off every few weeks) and a gurgling sound from the heater core on startup. Because the leak is small early on, it is frequently misdiagnosed as a bad coil or plug before the head gasket is identified. Left unaddressed it progresses to overheating and possible head/block damage.

Common Symptoms

  • Cold-start misfire on cylinder 4 or 6
  • Slowly disappearing coolant with no visible external leak
  • Need to add coolant every few weeks
  • Gurgling from heater core on startup
  • Check Engine Light with P0304/P0306
  • White exhaust vapor on cold start
  • Eventual overheating

How to Fix

Diagnose with a cylinder leak-down/compression test, a combustion-gas (block) test of the coolant, and cooling-system pressure testing to confirm internal coolant loss before replacing parts. The repair is to remove the heads and replace both head gaskets with the updated/superseded gasket, resurface and inspect the heads, and refill with the correct coolant. Replace head bolts per spec if torque-to-yield. Verify no oil-in-coolant or coolant-in-oil contamination that would indicate further damage.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 04112-0P061 genuine 1GR-FE valve-grind gasket kit

    supply the coordinated top-end seals for a confirmed head-gasket repair after inspection and machine work Fitment/availability: 2005-2012 Toyota Tacoma 4.0L 1GR-FE top-end gasket kit; supersedes 04112-31080 and 04112-0P060, with VIN conf…

    ToyotaPartsNow
  • Toyota 90910-02162 / 90910-A2006 genuine cylinder-head bolt

    replace each head fastener that the factory procedure identifies as non-reusable or out of specification Fitment/availability: Individual 1GR-FE cylinder-head fastener application; 90910-02162 is superseded by 90910-A2006 and the repair …

    ToyotaPartsDeal

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Typical repair cost:$1,500 - $3,500
Sources for this issue (3)
  • V6 1GR-FE Head Gasket Failure — Tacoma Worldforum
  • P0304 on 2005-2015 Toyota Tacoma 4.0L V6: Cylinder 4 Misfire Causes — Go-Partsarticle
  • Toyota Tacoma Head Gasket Replacement Cost — RepairPalarticle

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Link to this issueError Codes:P0171P0174P0300P0128

The Toyota Tercel equipped with the 1.5L 3E-E and 5E-FE engines is prone to head gasket failure, particularly at higher mileages. The gasket material deteriorates over time, allowing coolant to leak externally or mix with engine oil. Overheating episodes accelerate gasket failure. The 5E-FE (1995-1999) is somewhat more reliable but still susceptible. Regular cooling system maintenance and avoiding overheating are key to longevity.

Common Symptoms

  • Coolant loss without visible external leak
  • White exhaust smoke (coolant burning)
  • Milky residue on oil filler cap
  • Engine overheating
  • Rough idle and misfire

How to Fix

Confirm head gasket failure with a cooling-system pressure test, combustion-gas block test, and compression or leak-down test, then inspect for coolant in the oil and cylinder head warpage after disassembly. Repair requires removing the cylinder head, resurfacing or replacing it if out of spec, and installing a new head gasket set with new head bolts, while also replacing the timing belt, water pump, thermostat, and any aged radiator hoses if service history is unknown. The radiator should be checked for flow restriction and the cooling fans verified so the root cause of overheating is corrected before reassembly. Typical repair cost is about $1,200-$2,200 depending on machine-shop work and whether related cooling-system parts are replaced.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Fel-Pro HS 9483 PT head-gasket set

    reseal a test-confirmed head-gasket failure on the early 3E-E branch after head and block inspection Fitment/availability: 1987-1994 Toyota Tercel 1.5L 3E/3E-E branch; confirm year, engine and required bolt set before ordering Fitment/av…

    PartsGeek
  • Fel-Pro HS 9494 PT head-gasket set

    reseal a test-confirmed head-gasket failure on the later 5E-FE branch after head and block inspection Fitment/availability: 1995-1999 Toyota Tercel 1.5L 5E-FE branch; verify VIN/engine and obtain the correct new head bolts separately Fit…

    PartsGeek

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Typical repair cost:$600 - $1,500
Sources for this issue (1)
  • Toyota Nation Forum - 5E-FE Head Gasket Replacement / Overheating Discussionforum

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Link to this issueError Codes:P0300

Tercels from 1991-1999 experience distributor failures at high mileage. The internal ignition coil and pickup coil degrade over time, causing intermittent no-start conditions, misfires, and stalling. The distributor cap and rotor also wear, but the internal electronics are the primary failure point. Moisture intrusion through cracked distributor caps accelerates failure.

Common Symptoms

  • Intermittent no-start condition
  • Engine misfires under load
  • Stalling at idle
  • Hard starting when hot
  • Check engine light

How to Fix

Replace the complete distributor assembly with a remanufactured or new unit ($200-$400 for parts). A simple cap and rotor replacement ($30-$50) may temporarily resolve symptoms if the internal electronics are still functional. Check the ignition coil resistance and pickup coil air gap before condemning the entire distributor.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Cardone Reman 31-77408 electronic distributor

    replace an electronically failed distributor only after the cap, rotor, coil, igniter, pickup, wiring and timing-belt branches are tested Fitment/availability: 1991 Toyota Tercel 1.5L all trims on the retailer-selected catalog page; the …

    AutoPartsPrime
  • Toyota 19101-11300 genuine distributor cap

    replace a cracked, carbon-tracked, moisture-damaged or worn distributor cap without condemning sound internal electronics Fitment/availability: 1992-production-change through 1994 Toyota Tercel 1.5L 3E-E distributor branch; verify the or…

    Toyota Parts Overstock / Lakeland Toyota
  • Toyota 19102-11031 genuine distributor rotor

    replace a burned, eroded or cracked rotor after visual inspection Fitment/availability: 1987-1994 Tercel 1.5L 3E/3E-E catalog branch, including this card's corrected 1991-1994 scope; superseded to 19102-11370 Fitment/availability: Ships …

    ToyotaPartsDeal

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Owner tips & cautions

  • TipBefore replacing the whole distributor, try a new cap, rotor, and ignition wires first. Fixed my no-start for $40 vs the $350 distributor.
Typical repair cost:$200 - $500
Sources for this issue (1)
  • YouTube - Diagnosing and Replacing Distributor on 1995 Toyota Tercel - ChrisFixvideo

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Link to this issueError Codes:P0420P0430P0300

As 4Runners accumulate miles, the catalytic converter loses efficiency and the ECU sets P0420 (Bank 1) and/or P0430 (Bank 2) when the downstream O2 sensor starts to mirror the upstream sensor. On the 4th-gen 1GR-FE, the primary cats are integrated into the exhaust manifolds, which makes them prone to cracking and internal breakdown with heat and age — a frequently searched and relatively expensive repair. Misfires, exhaust leaks, or a failing rear O2 sensor can also trip the code, so diagnosis before parts replacement matters.

Common Symptoms

  • Check engine light with P0420 and/or P0430
  • Passed-then-failed emissions / smog test
  • Slight loss of power or fuel economy at high mileage
  • Rattle from the exhaust manifold/cat (broken internal substrate)
  • Sulfur/rotten-egg smell

How to Fix

Diagnose before buying a cat: scan for misfire codes (P030x/P0300), check for exhaust leaks upstream, and compare upstream vs downstream O2/A-F sensor waveforms. If sensors and exhaust are healthy and the downstream signal tracks the upstream, replace the failed converter. On 4th-gen 4.0L trucks the failure is usually the passenger-side (Bank 1) manifold-integrated cat. Use OEM or a high-quality CARB-compliant converter; a common contributing fix is the Bank 1 Sensor 2 (downstream) O2 sensor (use Denso). Sensor-only fixes run $100-300; converter replacement is the expensive path.

Typical repair cost:$150 - $2,500
Sources for this issue (2)
  • P0420 on 2003-2009 Toyota 4Runner 4.0L V6: Causes and Fixes — Go-Partsarticle
  • P0420 code? READ THIS BEFORE REPLACING CATALYTIC CONVERTER — Toyota-4Runner.orgforum

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Link to this issueError Codes:P0300P0301P0303P0305

Early 4th-generation 4Runners with the 4.0L 1GR-FE V6 are known for head gasket failures, often presenting as an external coolant leak near the rear of the passenger-side cylinder head. Owners report gradual coolant loss, sweet smell, overheating risk, and misfires if the leak worsens. The issue is widely discussed in owner communities and repair databases, especially on 2003-2006 trucks.

Common Symptoms

  • slow coolant loss with no obvious front-engine leak
  • sweet coolant smell
  • coolant residue on rear of engine
  • overheating
  • rough running on cold start
  • misfire

How to Fix

Pressure-test the cooling system, inspect for coolant residue at the rear of the heads, and check for combustion-gas intrusion if overheating or misfires are present. Repair typically involves head gasket replacement, machine-shop inspection of the heads, and replacement of related seals, head bolts, water pump, and timing components as needed. Continuing to drive with low coolant can lead to severe engine damage.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Fel-Pro HS 26330 PT complete cylinder-head gasket set

    complete gasket-set branch after a head-gasket failure is confirmed and both heads are inspected Fitment/availability: 2003-2009 Toyota 4Runner 4.0L V6 1GR-FE according to retailer; review is for 2003-2006 and head bolts are explicitly n…

    PartsGeek
  • Fel-Pro ES 72249 cylinder-head bolt set

    new torque-to-yield head bolts required with the approved gasket-set repair Fitment/availability: 2003-2020 Toyota 4Runner 4.0L V6 listing; confirm 1GR-FE VIN and required set quantity with the service procedure before purchase Fitment/a…

    PartsGeek

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Typical repair cost:$1,800 - $4,000
Sources for this issue (3)
  • Motor Biscuit: The Truth About the Toyota 4Runners V6 Problemsmedia
  • 4Runners.com: 4.0L V6 Blown Head Gasketforum
  • Expedition Portal: Head gasket repair on 4th gen 4runner V6forum

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Link to this issueError Codes:P0171P0174P0300P0128

The 2.4L 22R-E engine in the Toyota Pickup is prone to head gasket failure, often presenting as coolant leaking externally from the rear of the cylinder head or mixing with engine oil. The single-layer gasket used in early production deteriorates over time. Overheating episodes dramatically accelerate gasket failure. The 22R-E is otherwise extremely reliable, and head gasket replacement extends engine life significantly. A multi-layer steel (MLS) gasket upgrade is recommended during repair.

Common Symptoms

  • External coolant leak from cylinder head area
  • White exhaust smoke
  • Coolant mixing with oil (milky dipstick)
  • Engine overheating
  • Coolant level dropping over time

How to Fix

Confirm head gasket failure with a cooling-system pressure test, combustion-gas/block test, compression or leak-down test, and inspection for coolant seepage at the rear of the cylinder head or oil contamination. Repair requires removing the cylinder head, checking it and the block deck for warpage/cracks, resurfacing the head if needed, and installing the updated Toyota head gasket or a quality MLS gasket set with new head bolts, plus replacing the thermostat and any aged hoses while the system is apart. Refill with fresh coolant and engine oil/filter, then verify radiator and fan clutch operation because prior overheating commonly causes repeat failures. Typical repair cost is about $1,200-$2,500 at a shop depending on machine work, while parts alone are often $200-$500.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Toyota 04112-35330 genuine 22R-E head gasket set

    OE head sealing set after diagnosis and surface measurement; half-moon cam plugs are not included Fitment/availability: 1985-1995 Toyota Pickup and 4Runner with fuel-injected 2.4L 22R-E; issue display must be limited to 22R-E Fitment/ava…

    YotaShop

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Typical repair cost:$500 - $1,500
Sources for this issue (3)
  • ToyotaNation: RESOLVED - 22R pinging head gasket failureforum
  • BAT Auto Technical: 1992 Toyota Pickup 22RE 2.4L Head Gasketforum
  • AutoPartsWD: Toyota 22R Engine Guide Specs, Reliability & Upgradesmedia

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Link to this issueError Codes:P0171P0174P0300P0128

The 3.4L 5VZ-FE V6 engine in 1995-1998 T100 trucks can develop head gasket leaks, typically presenting as external coolant leaks from the rear of the passenger-side cylinder head. The gasket material deteriorates over time, especially with infrequent coolant changes. While the 5VZ-FE is generally a reliable engine, the head gasket is its most common failure point. The V6 configuration makes the rear head gasket particularly labor-intensive to access.

Common Symptoms

  • Coolant leak from rear of engine
  • Engine overheating
  • White exhaust smoke
  • Coolant loss without obvious external leak
  • Rough idle and misfires

How to Fix

Confirm the failure with a cooling-system pressure test, combustion-gas/block test, and inspection for coolant seepage at the rear of the passenger-side cylinder head; if overheating or coolant loss is present, also check compression/leakdown and inspect spark plugs for steam-cleaning. Repair requires removing both cylinder heads, checking head and block deck flatness, machining the heads if needed, and installing updated OEM-style head gaskets with new head bolts, intake/exhaust gaskets, thermostat, and fresh coolant; replace the timing belt, water pump, and cam/crank seals at the same time if service history is unknown because labor overlap is significant. Typical cost is about $2,000-$3,500 at an independent shop, with higher totals if the heads are cracked or extensive machine work is required.

What you need to fix it

Only diagnosis- and fitment-reviewed repair parts are linked here.

  • Fel-Pro HS 9227 PT-1 5VZ-FE cylinder-head gasket set

    reseal both inspected cylinder heads after diagnosis, flatness measurement and any required machine work Fitment/availability: 1995-1998 Toyota T100 3.4L V6 5VZ-FE; includes top-end gaskets and seals but explicitly excludes head bolts Fi…

    PartsGeek
  • AISIN TKT-005 timing-belt and water-pump kit

    complete the labor-overlap timing service only when history is unknown, due, contaminated or inspection shows wear Fitment/availability: 1995-1998 Toyota T100 3.4L 5VZ-FE; kit includes water pump, timing belt and pulleys but not the hydr…

    Walmart

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Typical repair cost:$1,000 - $2,500

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Link to this issueError Codes:P0300P0301P0302P0303P0304

Toyota T-SB-0010-24 applies to 2018-2024 Camry vehicles with the A25A-FKS engine that misfire after a cold soak when engine-coolant temperature in freeze-frame data is 14-41 degrees F. The bulletin identifies P030027, P030000, P030100, P030200, P030300, and P030400. It does not authorize lash-adjuster replacement from a rough-start complaint alone: compression, spark plugs and coils, direct- and port-injector resistance, and the fuel system must first meet specification.

Common Symptoms

  • Cold-soak misfire with coolant freeze-frame temperature of 14-41 degrees F
  • Rough running immediately after an eligible cold soak
  • MIL with one or more exact T-SB-0010-24 misfire DTCs

How to Fix

Confirm that an exact listed DTC is present and that freeze-frame coolant temperature was 14-41 degrees F. Follow T-SB-0010-24 to verify cylinder compression, spark-plug and ignition-coil operation, direct- and port-injector resistance, and fuel-system operation. If every prerequisite is within specification and the bulletin's decision path is satisfied, replace all eight exhaust-side hydraulic lash adjusters and required one-time-use seals/gaskets using the bulletin and current VIN-specific parts information. Do not substitute a generic P0300 diagnosis, assume intake carbon is the cause, or order an old/superseding part number from this card.

Owner tips & cautions

  • TipSave the exact seven-character DTC and freeze-frame coolant temperature before clearing codes; both determine whether T-SB-0010-24 applies.
  • WarningThe bulletin requires compression, ignition, both injector systems, and fuel-system checks before eight lash adjusters are authorized, and it expressly says not to use superseding part numbers from its table.
Sources for this issue (1)
  • Toyota T-SB-0010-24: A25A-FKS Cold-Start Misfiretsb

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P0300 code reference

General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.

Frequently asked questions

What does P0300 mean on a Toyota?

P0300 stands for "Random/Multiple Cylinder Misfire Detected." P0300 means the engine computer detected misfires occurring randomly or across multiple cylinders rather than in one specific cylinder. A misfire is when a cylinder fails to ignite its fuel-air mixture properly, which the computer senses through small fluctuations in crankshaft speed. Because it's not isolated to one cylinder, the cause is usually something that affects the whole engine — like fuel, air, or ignition system problems — rather than a single coil or plug. Persistent or heavy misfiring wastes fuel, runs rough, and can damage the catalytic converter, which is why a flashing check engine light should be taken seriously. On Toyota it is documented across 20 models: GR86, Prius, Avalon, Solara, GR Corolla, Celica, Corolla, Highlander, Matrix, Paseo, 86, Previa, Land Cruiser, Yaris, Tacoma, Tercel, 4Runner, Pickup, T100, Camry.

What are the most common causes of P0300?

The most common causes of P0300 are: Worn or fouled spark plugs (across cylinders), Vacuum or intake air leak, Weak fuel pump, clogged fuel filter, or low fuel pressure, Failing ignition coils or worn spark plug wires, Dirty or faulty mass airflow (MAF) sensor, Clogged or dirty fuel injectors, Faulty crankshaft/camshaft position sensor, Low compression or EGR/PCV system faults. The specific cause varies by vehicle.

How much does it cost to fix P0300 on a Toyota?

Published repair estimates on Toyota range from $60 to $5,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.

Related codes

  • P0301 · Cylinder 1 Misfire Detected
  • P0302 · Cylinder 2 Misfire Detected
  • P0303 · Cylinder 3 Misfire Detected
  • P0304 · Cylinder 4 Misfire Detected
  • 00522 · Engine Coolant Temperature Sensor (G62): Open Circuit / Short to Positive (B+)
  • 16500 · Engine Coolant Temp. Sensor (G62): Implausible Signal
  • 16502 · Engine Coolant Temperature Sensor (G62): Signal too High
  • 16566 · Mass Air Flow Sensor Signal Too Low (VAG)

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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.

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