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Toyota · Engine · Moderate code

P0301 on Toyota: How to Diagnose & Fix

Cylinder 1 Misfire Detected

14 Toyota models · 23 documented issues · 10 critical · $50-$5,000 repair

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P0301 by Toyota model

  • 2022-2023GR861
  • 2004-2018Prius2
  • 2005-2018Avalon1
  • 2023-2025GR Corolla1
  • 2000-2005Echo1
  • 2000-2010Corolla3
  • 2001-2019Highlander3
  • 2013-2020862
  • 1991-1997Previa2
  • 2007-2018Yaris2
  • 2005-2023Tacoma2
  • 2009-2015Venza1
  • 2003-20064Runner1
  • 2018-2024Camry1
  • FAQ

P0301 on other makes

  • Acura
  • Alfa Romeo
  • Audi
  • Bmw
  • Buick
  • Cadillac
  • Chevrolet
  • Chrysler
  • Dodge
  • Ford
  • Genesis
  • Gmc
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P0301 by Toyota model

  • 2022-2023GR861
  • 2004-2018Prius2
  • 2005-2018Avalon1
  • 2023-2025GR Corolla1
  • 2000-2005Echo1
  • 2000-2010Corolla3
  • 2001-2019Highlander3
  • 2013-2020862
  • 1991-1997Previa2
  • 2007-2018Yaris2
  • 2005-2023Tacoma2
  • 2009-2015Venza1
  • 2003-20064Runner1
  • 2018-2024Camry1
  • FAQ

P0301 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
All Toyota Avalon 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

Research This Issue

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 →
Community reported
140 owners
Link to this issueError Codes:P0301P0302P0303P0304

The 1.5L 1NZ-FE engine in the Echo develops oil leaks at the valve cover gasket and the oil filler cap seal. The rubber valve cover gasket hardens with age and heat cycling, allowing oil to seep down the side of the engine onto the exhaust manifold, producing a burning oil smell. The spark plug tube seals (integral to the valve cover gasket) also leak, allowing oil to pool around the spark plugs and cause misfires. The oil filler cap O-ring also dries out and leaks.

Common Symptoms

  • Burning oil smell from engine bay
  • Oil dripping down side of engine
  • Oil pooling around spark plugs (misfires)
  • Visible oil around valve cover edges
  • Check engine light with misfire codes

How to Fix

Replace the valve cover gasket with a Toyota OEM gasket kit that includes spark plug tube seals. Clean all oil residue from the exhaust manifold after replacing. Replace the oil filler cap O-ring (or the entire cap for $10). Apply a thin bead of RTV sealant only at the cam cap corners where the valve cover gasket doesn't seal perfectly.

What you need to fix it

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

  • Toyota 11213-21011 genuine cylinder-head-cover gasket

    replace the molded valve-cover gasket after confirming leakage at the cover joint Fitment/availability: 2000-2005 Toyota Echo 1.5L 1NZ-FE; replaces 11213-21010; confirm VIN/current supersession Fitment/availability: Ships in 1-3 business…

    ToyotaPartsDeal
  • Toyota 90430-37140 genuine oil-filler-cap gasket

    replace the cap seal when cleaned-and-rechecked evidence identifies seepage at the oil filler cap Fitment/availability: 2000-2005 Toyota Echo 1.5L 1NZ-FE; exact filler-cap gasket catalog fitment; confirm VIN/current supersession Fitment/…

    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

  • TipThis is a 30-minute DIY job — just 4 bolts hold the valve cover on. Apply a tiny bead of RTV at the two front cam cap corners for a perfect seal.
  • WarningDon't ignore oil pooling around spark plugs — oil-soaked ignition coils fail prematurely and cost $60+ each
Typical repair cost:$50 - $250

Research This Issue

Based on 140 owner reports

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Community Reported
Low Confidence140 owner reportsLast reported by owners Mar 2026Reviewed Mar 2026
All Toyota Echo known issues →
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…

    ToyotaPartsDeal
  • 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…

    ToyotaPartsDeal
  • 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 …

    ToyotaPartsDeal
  • 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…

    ToyotaPartsDeal
  • 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…

    ToyotaPartsDeal
  • 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

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:$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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Community Reported
Medium ConfidenceVerifiedReviewed Jun 2026
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.

    ToyotaPartsDeal
  • 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.

    ToyotaPartsDeal
  • 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

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:$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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Community Reported
Medium ConfidenceVerifiedReviewed Jul 2026
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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Community Reported
Medium Confidence
All Toyota Highlander known issues →
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

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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.

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 (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:P0301P0302P0303P0304

Early 2013-2014 Toyota 86 models were subject to a valve spring recall similar to the later GR86 issue. Improperly manufactured valve springs could fracture, causing engine misfires and potential internal engine damage. The FA20 engine's boxer layout means a broken valve spring piece can fall into the cylinder and cause catastrophic piston damage.

Common Symptoms

  • Engine misfire
  • Rough idle
  • Check engine light
  • Loss of power on one cylinder
  • Metallic ticking from engine

How to Fix

Contact Toyota dealer for recall verification and service. The recall involves replacing all 16 valve springs with updated parts. If the engine was damaged before the recall was performed, Toyota may authorize goodwill engine repair or replacement. The recall service is free of charge.

Owner tips & cautions

  • WarningCheck your VIN on toyota.com/recall immediately. If the valve spring recall hasn't been done, stop driving until it is. A broken spring at 7,000 RPM will destroy the engine.
Typical repair cost:$0 - $0
Sources for this issue (1)
  • Reddit r/Toyota86 Thread Discussing Valve Spring Recall and Engine Issuesforum

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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: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:P0420P0301

The 1NZ-FE is not an oil burner when new, but owners on yarisworld report it developing meaningful consumption once the rings wear - reports cluster around a half-dipstick per 2,500 miles up to roughly one liter per 2,000 miles. The causes are the usual pair: coked/stuck oil control rings (aggravated by extended drain intervals and short-trip city driving, which is exactly how most Yaris live) and hardened valve stem seals that let oil down the guides on overrun. Because Toyota's own manual states a very permissive 'normal' consumption figure, dealers frequently dismiss the complaint. The danger is not the engine failing - it is the owner not checking the dipstick between 5,000-mile changes and running it dry, or the oil burn slowly poisoning the catalytic converter.

Common Symptoms

  • Low oil light or low dipstick well before the next service
  • Blue smoke on cold start or when lifting off after a long downhill
  • Oil consumption of roughly a quart every 1,000-2,500 miles
  • Fouled spark plugs
  • Eventual P0420 as the catalyst is contaminated

How to Fix

Confirm with a documented consumption test (measured fill, drive 1,000 miles, re-measure). If it is valve stem seals, expect blue smoke only on cold start and after long decel - seals can be done with the head on using a rope/air-hold method. For stuck oil control rings, a piston soak (solvent down the plug holes overnight, then a full oil and filter change) frequently restores compression and cuts consumption. Beyond that it is a ring job. Regardless: shorten the oil change interval, use the correct 0W-20/5W-20 grade, and check the dipstick every fuel fill.

Typical repair cost:$150 - $2,500
Sources for this issue (3)
  • Oil consumption issues in Yaris? - Toyota Yaris Forums (yarisworld.com)forum
  • Yaris burning oil - Toyota Yaris Forums (yarisworld.com)forum
  • Toyota Oil Burn Fixes: Piston Soaking & Ring Cleanup - 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:P0303P0301P0306

P0303 indicates a misfire on cylinder 3. On the 3rd-gen Tacoma 3.5L 2GR-FKS V6, owners commonly trace this to a failed coil-on-plug ignition coil or spark plugs that are worn or past their ~60k-mile service window. Toyota has acknowledged coil-related P0301-P0306 misfires on its 2GR family and issued a technical service bulletin (L-SB-0044-19 / NHTSA MC-10169331) updating the older ignition coil part number (90919-02280) to a revised coil (90919-A2013). Off-brand spark plugs of the wrong heat range can also induce misfires on these engines even when new, because Toyota's ignition system is tuned to specific Denso/NGK plugs. The COP layout makes cylinder 3 easy to isolate by coil swap.

Common Symptoms

  • Rough idle / vibration
  • Flashing or steady check engine light
  • Stumble or hesitation under load
  • Reduced power and fuel economy
  • Occasional hard start

How to Fix

Swap the cylinder 3 coil to an adjacent cylinder and re-scan; if the misfire follows, replace the coil (use the updated Toyota coil per TSB L-SB-0044-19 / MC-10169331 where applicable). Replace spark plugs as a set with OEM-spec Denso/NGK iridium plugs at the correct gap/heat range if they are worn or aftermarket. Verify the coil connector and check the injector/compression on cylinder 3 only if coil and plug are confirmed good.

What you need to fix it

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

  • Toyota 90919-A2008 genuine 2GR-FKS ignition coil

    replace the cylinder 3 coil only when the misfire follows it or testing proves it failed Fitment/availability: 2016-2023 Tacoma 3.5L 2GR-FKS Type A ignition-coil branch; one per cylinder, six engine-wide, with VIN confirmation required F…

    ToyotaPartsDeal
  • Toyota 90919-01263 genuine FK20HBR8 iridium spark plug

    replace a fouled or damaged cylinder 3 plug, or all six as a matched set when wear or service interval supports replacement Fitment/availability: 2016-2023 Tacoma 3.5L 2GR-FKS FK20HBR8 branch; six required for a complete set and VIN conf…

    ToyotaPartsDeal

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Typical repair cost:$100 - $400
Sources for this issue (4)
  • Toyota TSB L-SB-0044-19 (NHTSA MC-10169331) — MIL ON with misfire DTCs P0301-P0306, ignition coil update 90919-02280 → 90919-A2013 (2GR engines)tsb
  • Ignition coil problems — 3rd Generation Toyota Tacoma Forum (Tacoma3G)forum
  • Still have P0303 code after plugs, wires and coil — Tacoma Forumforum
  • P0303 Engine Code | Cylinder 3 Misfire Detected (Toyota Tacoma) — FIXDarticle

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Link to this issueError Codes:P0301P0302P0303

The first-generation Venza (2009-2015) develops valve cover gasket oil leaks, particularly the V6 3.5L models. Oil seeps from the valve cover gasket onto the exhaust manifold, creating a burning oil smell. The leak progresses over time and can foul spark plug tubes, causing misfires. The V6 rear valve cover is harder to access due to its position against the firewall.

Common Symptoms

  • Burning oil smell from engine bay
  • Visible oil on valve cover edges
  • Oil in spark plug wells causing misfires
  • Low oil level between changes
  • Smoke from engine area on hot days

How to Fix

Replace valve cover gaskets and spark plug tube seals. For the V6, both front and rear valve covers should be done together. Use genuine Toyota gaskets for best sealing. Clean the valve cover and cylinder head mating surfaces thoroughly before installing new gaskets. The I4 is a straightforward 1-2 hour job. The V6 rear cover is 3-4 hours due to access difficulty.

What you need to fix it

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

  • Fel-Pro VS 50825 R 2.7L valve-cover gasket set

    reseal a test-confirmed 2.7L cylinder-head-cover leak Fitment/availability: 2009-2015 Toyota Venza 2.7L 1AR-FE branch; confirm year, engine and included VVT/oil-control seals before purchase Fitment/availability: Sold and shipped by Walm…

    Walmart
  • Fel-Pro VS 50682 R 3.5L valve-cover gasket set

    reseal test-confirmed front and rear 3.5L cylinder-head-cover leaks with the complete engine-matched set Fitment/availability: 2009-2016 Toyota Venza 3.5L 2GR-FE catalog application; cross-references Toyota 11213-0P010 and 11214-31020, w…

    FinditParts

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Owner tips & cautions

  • TipIf oil is getting into the spark plug tubes, change the plugs when you do the gaskets. Oil-soaked plug boots will misfire even after the leak is fixed. Do both valve covers on the V6 while you're in there.
Typical repair cost:$200 - $600
Sources for this issue (1)
  • YouTube - How to Replace Valve Cover Gasket on 3.5L V6 Toyota Venza by EricTheCarGuyvideo

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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: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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P0301 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 P0301 mean on a Toyota?

P0301 stands for "Cylinder 1 Misfire Detected." P0301 means the engine computer detected a misfire specifically in cylinder 1 — the spark didn't ignite the fuel properly, or the fuel/air mix didn't burn as it should. The computer detects this by sensing tiny variations in crankshaft speed each time a cylinder fires. A misfire wastes fuel, raises emissions, and can damage the catalytic converter if it's severe or persistent (a flashing check engine light usually warns of active, converter-damaging misfires). Because the code points to one specific cylinder, the cause is usually an ignition, fuel, or compression problem isolated to that cylinder. On Toyota it is documented across 14 models: GR86, Prius, Avalon, GR Corolla, Echo, Corolla, Highlander, 86, Previa, Yaris, Tacoma, Venza, 4Runner, Camry.

What are the most common causes of P0301?

The most common causes of P0301 are: Worn or fouled spark plug in cylinder 1, Failed ignition coil or coil pack for cylinder 1, Faulty or clogged fuel injector for cylinder 1, Vacuum or intake air leak affecting that cylinder, Bad spark plug wire (on applicable engines), Low compression (worn rings, leaking or burnt valve, head gasket), Carbon buildup on intake valves, Wiring or connector fault to the coil or injector. The specific cause varies by vehicle.

How much does it cost to fix P0301 on a Toyota?

Published repair estimates on Toyota range from $50 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

  • P0300 · Random/Multiple Cylinder 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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