2012 Jeep Wrangler Engine Problems (179 Complaints)

Engine & cooling

While driving my 2012 Jeep Wrangler Sport, the vehicle experienced a sudden and severe loss of engine power due to a cylinder failure on the left/driver-side cylinder head (cylinder #2). This defect causes the engine to experience persistent cylinder misfires, resulting in severe engine stumbling, hesitation, and a dangerous drop in acceleration capabilities. This creates an immediate safety hazard when attempting to merge onto high-speed highways, pull out into active traffic, or navigate intersections, as the...

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vehicle cannot accelerate predictably to match traffic speeds. Furthermore, the persistent misfire causes unburned fuel to dump into the exhaust system, creating a secondary risk of catalytic converter overheating, damage to the exhaust system, and a potential engine bay fire hazard. This vehicle has only 86,000 original miles. This specific 3.6L Pentastar engine generation is subject to a widely documented manufacturing defect involving premature valve seat and head failure, which manifests as an unpredictable and sudden loss of motive power while the vehicle is in motion.

Engine & cooling

The engine's cylinder head/valve train has failed internally, allowing combustion gases to enter the cooling system - confirmed via a chemical block test performed by a master automotive technician on November 29, 2024, which verified combustion gases present in the coolant. This is a widely documented defect on this engine and model year, related to valve seat erosion in the cylinder head. Symptoms first appeared in June 2018 as an unusual higher-pitched, stressed sound from the engine. Over time this progressed...

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to recurring, confirmed misfires on cylinders 1, 2, 3, and 5 (diagnostic codes P0300, P0301, P0302, P0303, P0305) and a mixture control fault (P219B). The check engine light has intermittently stayed illuminated for months at a time, then gone off for extended periods while the same fault codes remain stored and confirmed by a diagnostic scanner - currently the light is off but the codes persist. The vehicle frequently runs rough enough that the engine must be turned off and restarted to temporarily return to closer-to-normal operation. Noticeable vibration is felt during much of this pattern. Spark plugs, ignition coils, oxygen sensors, and the PCV valve have all been inspected/replaced and ruled out as the cause on multiple occasions over more than a year, isolating the cause to the cylinder head itself. This creates a driveability and potential stalling/hesitation risk, though no crash, injury, or fire has occurred to date. The vehicle has not been formally inspected by the manufacturer, police, or an insurance representative. The affected component remains in the vehicle and is available for inspection upon request.

Engine & cooling

The contact owns a 2012 Jeep Wrangler. The contact stated that while driving at 20 MPH, the check engine warning light illuminated. The local dealer was contacted, but the vehicle was not diagnosed or repaired. The vehicle was taken to an independent mechanic, where a scan was completed, and diagnostic trouble codes for the Emissions, engine misfire, timing chain, and crank position sensor failures were displayed. The manufacturer was not contacted. The failure mileage was approximately 71,756.

Electrical systemAirbagsEngine & cooling

My complaint is that I was sold a dangerously defective vehicle with a known, unrepaired "stop driving" airbag safety recall, was not warned about the deadly risk, and am now being told to move and tow the car in direct contradiction to official safety instructions. ### Factual background - The vehicle I purchased has a Takata-type airbag safety recall that carries a formal "do not drive" or "stop driving" warning because the airbag can explode and kill or severely injure occupants, even in a minor...

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crash.[1][2][3][4] - Federal safety authorities have confirmed that at least 28-29 people in the United States have been killed and more than 400 injured by exploding Takata airbag inflators.[3][4][5][1] - I received the recall notice about two months ago, but I was told the repair parts were back-ordered, which delayed fixing the deadly defect through no fault of my own.[1][3] - During this delay, the vehicle's battery became completely dead, and I am now being told by the recall and towing company that I must make sure the car is taken out of the garage, which would require entering and moving a vehicle I have been legally and explicitly told not to drive. ### Legal and safety concerns - Official guidance from the National Highway Traffic Safety Administration (NHTSA) and the manufacturer is that vehicles under this Takata "do not drive" recall must not be driven at all until the defective airbag is replaced, because even a minor collision can cause the inflator to explode and send metal shrapnel into the cabin.[2][4][3][1] - The instruction to move or drive the car out of the garage conflicts with this clear safety warning and effectively asks me to assume a risk that has already caused multiple deaths and serious injuries nationwide.[4][5][2][3][1] - Federal law prohibits franchised dealers from selling new vehicles with unrepaired safety recalls, and legal experts warn that selling used vehicles with undisclosed safety defects can expose sellers and dealers to

Engine & cooling

The vehicle exhibits a persistent valvetrain ticking noise associated with the rocker/lifter/cam components of the 3.6L Pentastar V6. The engine makes a rhythmic metallic tapping at idle and during acceleration. The noise has progressively worsened, leading to rough idle and occasional misfires. This issue is documented in multiple Stellantis technical service bulletins (e.g., TSB 09-015-24 and TSB 09-011-25) which attribute the noise to hydraulic lash adjuster and cam/rocker wear. If unaddressed, the failure can...

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cause camshaft damage, metal debris contamination, loss of power and potential engine stall, posing a safety risk. The vehicle is available for inspection. The problem has been confirmed by independent mechanics who recommend replacement of the rocker arms, lifters and camshaft to prevent catastrophic engine failure.

Engine & cooling

The vehicle exhibits a persistent valvetrain ticking noise associated with the rocker/lifter/cam components of the 3.6L Pentastar V6. The engine makes a rhythmic metallic tapping at idle and during acceleration. The noise has progressively worsened, leading to rough idle and occasional misfires. This issue is documented in multiple Stellantis technical service bulletins (e.g., TSB 09-015-24 and TSB 09-011-25) which attribute the noise to hydraulic lash adjuster and cam/rocker wear. If unaddressed, the failure can...

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cause camshaft damage, metal debris contamination, loss of power and potential engine stall, posing a safety risk. The vehicle is available for inspection. The problem has been confirmed by independent mechanics who recommend replacement of the rocker arms, lifters and camshaft to prevent catastrophic engine failure.

Engine & cooling

Timing chain and misfire bank 1 and bank 2 crank shaft and crank sensor issues.

Engine & cooling

I am reporting a persistent and safety-relevant defect in my 2012 Jeep Wrangler with the 3.6L Pentastar engine. The vehicle is experiencing misfires on multiple cylinders, especially cylinders 1 and 5, triggering codes P0300, P0301, and P0305. These misfires result in loss of power, hesitation, and rough idle, creating serious safety concerns during acceleration or highway driving. Despite replacing spark plugs, ignition coils, the crankshaft position sensor, purge valve, and both oxygen sensors, the problem...

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continues. The vehicle has just 83,000 miles and is currently at a certified third-party repair facility. Multiple mechanics believe the issue stems from known defects in the left (Bank 1) cylinder head or valve train components - an issue Chrysler previously acknowledged via TSBs and a 10yr/150k mile extended warranty on select VINs. I contacted Jeep Cares and requested goodwill support, but they refused to even discuss the issue because my Jeep is not at a dealership. This leaves owners like me with limited, expensive options despite being affected by a well-documented defect. Jeep forums and independent shops have seen widespread misfire problems on early 3.6L Pentastar engines, especially 2012-2013 models. I urge NHTSA to investigate this pattern of failure. The misfires impact driveability and safety, and the manufacturer has not offered sufficient resolution or consistent support to affected customers. I'm happy to provide additional information, documentation, or diagnostics.

Engine & coolingFire

Engine spontaneously caught fire. It had been parked for hours before it happened. Everything under the hood was totaled

BrakesEngine & cooling

The contact owns a 2012 Jeep Wrangler. The contact stated that while operating the vehicle the ABS, Traction Control and check engine warning lights had remained illuminated. The contact indicated that while pressing the brake pedal to stop, the brake pedal extended to the floor causing the braking distance to become extended. The vehicle was taken to the local dealer who diagnosed that the ABS module was faulty and needed to be replaced. The vehicle was not yet repaired. The manufacturer was notified of the failure but no assistance was offered. The failure mileage was 55,000.

Engine & cooling

In my 2012 Jeep I had to replace the engine and catalytic converters. The engine number 3 cylinder failed due to excessive ware causing lower compression. After the engine (long block) was replaced, one of the cylinders was miss firing. This miss firing was traced to micro cracks in the plastic/composite intake manifold (original and not part of the engine replacement). Because these micro cracks changed the fuel air ratio on specific cylinders by leaning out the cylinders near the cracks this lean mixture would...

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cause the affected cylinders to run hot that would lead to both the excessive ware on the one cylinder and would comprise the catalytic converters. Because this change in fuel air mixture was caused by the intake manifold and Jeep does not have any inspection requirements or methods for this item and even after the Jeep Dealer did a full diagnosis using their factory specified equipment the issue with the manifold was not found. My local AMMCO shop found the cracking in the manifold that was the route cause of the problem.

Engine & cooling

Jeep Wrangler 3.6 liter 90k miles lifter making loud noise. Seems you had a recall about this on the 2012 and guess I missed out

Engine & cooling

6 days after an oil change, the temp gauge while driving went from cool to hot in under a mile and the engine temp light came on. There was coolant all over the underside of the car it was near catastrophic. I had to have it towed to the dealership for repairs. The faulty part was the oil filter adapter it was cracked by over tightening of the oil filter.

Transmission & drivetrainEngine & coolingFuel system

Engine Stalls Randomly while Driving. Will crank over several times and over approx 10-15 min. of cranking(Say every 3-5min) vehicle will and will restart. No check engine lights and no warning. The loss of power can be dangerous since brake and steering assist require engine to be running. Vehicle will be fine for several days local commute and problem will recur without warning, usually on longer commute. Vehicle is unsafe and unpredictable.

Engine & cooling

Cam sensor failed. Check engine light and traction control light appeared. Replaced and same problems occurred. May be wiring or cam/rocker issues.

Engine & cooling

The contact owns a 2012 Jeep Wrangler. The contact stated while starting the vehicle, there was an abnormal burning odor around the vehicle. The contact stated while driving 45 MPH and other various speeds the burning odor was still present. The check engine warning light illuminated with the temperature gauge rising from normal to hot. An audible alarm was heard during the failure. The vehicle was driven to the residence and then towed to a dealer. The vehicle was diagnosed and determined that the radiator needed...

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to be replaced. The contact had the vehicle towed to an independent mechanic who determined that coolant was leaking into the cylinder head. The vehicle had not been repaired. The manufacturer had been informed of the failure. The failure mileage was approximately 60,000.

Transmission & drivetrainEngine & cooling

While driving the car randomly stalls. I lose power steering and braking. The car will not restart. This issue has been recorded by the dealer. The vehicle was last inspected on July 5th. I have been issued a Jeep Care case manager, case # 82963828. There are no warnings, while driving makes a left-hand turn the car just stalls!