P0420 on Jeep: How to Diagnose & Fix
Catalyst System Efficiency Below Threshold (Bank 1)
6 Jeep models · 9 documented issues · 3 critical · $50-$8,500 repair
P0420 on Jeep by model: symptoms, diagnosis and fix
The 2.4L Tigershark MultiAir engine suffers from defective piston rings allowing oil to burn in combustion chamber. Owners report consuming 1 quart per 1,000 miles. Engine can stall when oil falls below 3.5 quarts without warning light.
Common Symptoms
- Consuming 1+ quart of oil every 1,000-2,000 miles
- Engine stalling without warning
- Oil light only after engine stalls
- Blue smoke from exhaust during acceleration
- Rough idle or misfires
How to Fix
FCA Warranty Extension XB1 covers excessive oil consumption for 7 years/100,000 miles. Engine recalibration/PCM software update can reduce consumption. Severe cases require engine replacement or rebuild with updated piston rings.
Owner tips & cautions
- WarningCheck oil level every 500-1,000 miles religiously
- TipDocument oil consumption with receipts for warranty claims
Sources for this issue (5)
- Valero Law: Class-Action over FCAs Tigershark Oil Consumption Defectmedia
- MyCarVoice: Fiat Chrysler 2.4L Tigershark Engine Class Action Settlement Announcedmedia
- Jeep Renegade Forum: 2.4L Tigershark Class Action Lawsuit and Oil Consumption Issuesforum
- The Lemon Firm: Jeep Cherokee 2.4L Tigershark Oil Consumption Causes Engine To Stallmedia
- Sauder Schelkopf: Jeep Excessive Engine Oil Consumption Class Action Investigationmedia
The 3.6L Pentastar V6 can consume oil at a rate higher than expected, sometimes requiring oil top-ups between changes. This is often related to piston ring design or valve guide seals. Chrysler considers up to 1 quart per 2,000 miles as within normal range.
Common Symptoms
- Oil level drops between changes
- Need to add oil frequently
- Blue smoke from exhaust
- Low oil pressure warning
- Oil smell from exhaust
How to Fix
Monitor oil level frequently. Use manufacturer-recommended oil viscosity. If consumption is excessive, dealer may perform oil consumption test for warranty coverage. Some engines have had piston/ring replacement under warranty.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar 68083202AC PCV valveOEMMopar 68083202AC
Replace a confirmed faulty or restricted PCV valve after the consumption and leak checks Fitment/availability: 2012-2018 Wrangler JK 3.6L; verify VIN.
- Genuine Mopar 68078776AA complete standard-size engine ring packageOEMMopar 68078776AA
Replace confirmed worn or defective standard-size rings during a measured professional rebuild Fitment/availability: 2012-2018 Wrangler JK 3.6L only after teardown measurements confirm standard-size rings and reusable bores/pistons; veri…
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
- TipGet a proper diagnosis before replacing parts - similar symptoms can have different causes
- TipSearch Jeep Wrangler forums and owner groups for real-world experiences and DIY guides
- TipGet multiple quotes from independent mechanics - dealer prices can be 2-3x higher for the same repair
TJ Wranglers with the 4.0L frequently develop catalytic converter deterioration, especially on higher-mileage vehicles and 2000-2006 emissions configurations using multiple converters/pre-cats. Owners commonly report a check-engine light with catalyst-efficiency codes, sulfur smell, rattling substrate, or loss of power if the converter begins to clog. This issue is well documented in owner complaints, repair databases, and Jeep service information.
Common Symptoms
- Check engine light
- P0420 or catalyst efficiency codes
- Rattling from catalytic converter
- Sulfur or rotten egg smell
- Reduced power at higher RPM
- Failed emissions inspection
How to Fix
Diagnosis involves checking for P0420/P0432-type efficiency codes, verifying upstream engine tune issues are not causing converter damage, and measuring exhaust backpressure or temperature differential if restriction is suspected. Repair is replacement of the failed converter assembly and any lazy O2 sensors if needed. Misfires, oil burning, or rich-running conditions should be corrected first so the new converter is not quickly damaged.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- MagnaFlow MF23297 Federal/EPA direct-fit rear catalytic-converter assemblyOEMMagnaFlow 23297 / etrailer MF23297
Not CARB compliant and retailer states it cannot be shipped to or used in California, Colorado, Maine or New York; verify the emissions labe
- aFe Power 47-48003 Federal direct-fit front catalytic-converter assemblyOEMaFe Power 47-48003 / Quadratec 17121-1000
Confirm wheelbase, emissions l
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
The 2.4L Tigershark engine may experience oil pump failure where insufficient oil pressure causes the engine to stall while driving. NHTSA Recall 17V-670 (October 2017) addressed oil pumps that would not deliver adequate pressure. The engine uses hydraulic valve actuators that rely on oil pressure, so low oil starves the valvetrain and causes sudden stalling. Excessive oil consumption between changes exacerbates the problem.
Common Symptoms
- Low oil pressure warning light
- Engine stalls while driving
- Oil level drops significantly between changes
- Ticking or knocking noise from engine
- Check engine light for oil pressure codes
- Vehicle will not restart after stalling
How to Fix
Check recall status (NHTSA 17V-670) for oil pump replacement at no cost. Monitor oil level every 1,000 miles and top off as needed. If experiencing oil consumption over 1 quart per 3,000 miles, have dealer perform an oil consumption test. Replace oil pump assembly if not covered by recall ($400-800). Use 0W-20 full synthetic oil per specification.
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Owner tips & cautions
- WarningCheck your oil level every 1,000 miles - the 2.4L Tigershark is known to consume oil and running low can destroy the engine
- TipIf your engine stalls from low oil pressure, do NOT try to restart immediately - check oil level first to avoid further damage
- TipVerify recall 17V-670 status at recalls.mopar.com - oil pump replacement is covered at no cost
Sources for this issue (2)
The catalytic converter on 2011-2016 front-wheel-drive Compass models with the 2.0L or 2.4L World Engine loses efficiency and exceeds NOx standards, a defect FCA acknowledged in emissions recall U67 (part of a roughly 862,000-vehicle campaign covering the Compass, Patriot and Caliber family). FCA attributed it to the combination of precious-metal loading, washcoat technology and fuel sulfur. Owners see a check engine light with P0420 that returns within a few hundred miles of clearing. Because the same engine family is prone to oil consumption and misfire, a converter that fails early is often being poisoned by oil or unburned fuel, so an underlying misfire or oil-burning condition must be corrected or the replacement converter dies too.
Common Symptoms
- Check engine light with P0420
- Sulfur or rotten-egg smell from the exhaust
- Failed state emissions test
- Reduced fuel economy and sluggish acceleration
- Rattle from under the vehicle if the substrate breaks up
How to Fix
Check the VIN for open emissions recall U67 first - FCA replaces the catalytic converter and reflashes the PCM at no charge on qualifying FWD 2.0L/2.4L cars. Otherwise, before condemning the converter, verify the downstream (B1S2) oxygen sensor is switching correctly on a scan tool at steady cruise, check for exhaust leaks ahead of the sensor, and repair any misfire or oil consumption. Then replace the catalytic converter with an OEM or CARB/EPA-compliant unit and clear codes.
Sources for this issue (3)
The 2.4L Tigershark MultiAir engine consumes oil at an abnormal rate, sometimes exceeding 1 quart per 1,000-2,000 miles. The MultiAir valve actuation system uses engine oil to operate the intake valves, and the system can develop internal leaks. Worn piston rings and valve seals also contribute. If oil level drops too low, the engine may stall or suffer catastrophic damage.
Common Symptoms
- Oil level drops significantly between changes
- Low oil pressure warning light
- Blue/gray smoke from exhaust
- Engine ticking or knocking at startup
- Check engine light for misfire codes
- Oil smell in cabin or under hood
How to Fix
Monitor oil level every 500-1,000 miles and top off as needed. If consumption exceeds 1 quart per 2,000 miles, have dealer perform an oil consumption test (typically requires 2-3 visits over 3,000 miles). Extended warranty may cover engine replacement if consumption is deemed excessive. Use only 0W-20 full synthetic oil. For high-mileage engines, switching to a high-mileage formulation (Valvoline MaxLife 0W-20) may reduce consumption slightly.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Pennzoil Platinum full-synthetic SAE 0W-20 motor oil, five quartsOEMPennzoil 550046127 / AutoZone 427013
Correct-specification oil for normal service and measured top-up while an owner or dealer documents consumption Fitment/availability: Renegade 2.4L requiring API-certified SAE 0W-20 meeting FCA MS-6395. Fill only to the dipstick/owner-ma…
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
- WarningCheck oil level every 1,000 miles minimum - the 2.4L Tigershark is a known oil consumer and running low will cause engine seizure
- TipDocument all oil consumption with receipts and records - needed if pursuing warranty engine replacement claim
Sources for this issue (2)
P0420 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 P0420 mean on a Jeep?
P0420 stands for "Catalyst System Efficiency Below Threshold (Bank 1)." P0420 means the engine computer determined the catalytic converter on Bank 1 isn't cleaning the exhaust as efficiently as it should. The computer compares the upstream and downstream oxygen sensors; a healthy converter stores and releases oxygen, so the downstream sensor should read fairly steady, while a worn one lets its readings mirror the upstream sensor. When that efficiency falls below a set threshold, this code is set. While it most often points to a worn-out catalytic converter, it can also be triggered by upstream problems like a faulty oxygen sensor or an exhaust leak, so the converter isn't always the actual fault. On Jeep it is documented across 6 models: Cherokee, Wrangler, Compass, Renegade, Comanche, Grand Cherokee.
What are the most common causes of P0420?
The most common causes of P0420 are: Worn-out or failing catalytic converter (Bank 1), Faulty or aged downstream (or upstream) oxygen sensor, Exhaust leak before or near the oxygen sensors, Engine running rich or lean (fuel trim issues), Misfires or oil/coolant contaminating the converter, Damaged or aftermarket low-quality catalytic converter, Faulty oxygen sensor wiring or connectors, Software/calibration needing update (on some vehicles). The specific cause varies by vehicle.
How much does it cost to fix P0420 on a Jeep?
Published repair estimates on Jeep range from $50 to $8,500 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.
Looking for P0420 on a different make?
View P0420 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.