Jeep Wrangler misfire problems

Filed Nov 1, 2026 · Engine · TN

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 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.

Filed Sep 19, 2026 · Fuel system · MO

Following completion of the 68C recall/software update around January 31, I noticed a significant change in the performance and drivability of my Jeep Wrangler 4xe. The most noticeable difference was a reduction in acceleration and overall power. The Jeep no longer had the quick, torquey response it previously had, which was one of the primary characteristics that attracted me to the 4xe. At times, pressing the accelerator resulted in noticeable hesitation and very weak acceleration. On one occasion, I pulled into traffic expecting the Jeep to accelerate normally, but it initially did not respond as expected, requiring substantially more throttle to get the vehicle moving. This created a legitimate drivability and safety concern. My impression was that the vehicle's hybrid/electric output had been significantly restricted following the recall update. Based on discussions occurring among other 4xe owners, similar behavior was being described as the vehicle being "nerfed," with reduced electrical output and battery utilization intended to protect the high-voltage battery. Regardless of the cause, the reduction in performance was clearly noticeable compared with how the Jeep drove before the update. In the period leading up to the eventual failure, I also noticed that the Jeep's acceleration felt increasingly abnormal. In retrospect, the change was noticeable enough that I suspected something might be developing before the vehicle ultimately failed. The Jeep later developed a high-voltage battery fault associated with battery-pack voltage variation/cell imbalance. The vehicle displayed warning messages, including "Service Charging System," along with a check-engine light. It also experienced rough idling and eventually became unreliable to start or move. The failure progressed to the point where the Jeep broke down while I was leaving home. After shutting the vehicle off, it would not reliably restart. At different points it briefly powered on, including while bei

Filed Sep 18, 2026 · Engine · SC

Misfire no. 4cylinder due to head gasket leak and coolant leaking into cylinder.

Filed Sep 13, 2026 · Airbags, Engine · AZ

I purchased this 2015 Jeep Wrangler Rubicon new and have maintained and serviced it regularly. At approximately 75,000–80,000 miles, the engine began developing a ticking noise from the passenger/right cylinder head area. The problem progressively worsened. At approximately 100,000 miles, repairs were performed involving the right-side cylinder head and camshaft because of camshaft/valvetrain wear and a persistent cylinder #2 misfire. The right-side cylinder head/camshaft area has required repair more than once. Rocker arms were also replaced, but the underlying problem continued. The vehicle now has approximately 150,000 miles. The engine recently shut down and developed a loud mechanical noise. Upon inspection, significant wear/damage was again found involving the right-side exhaust camshaft/valvetrain, and there are concerns involving the timing chain/tensioning system. A failure of these components while driving could cause sudden engine shutdown or loss of power, creating a safety risk. The vehicle has also developed electrical/safety-related problems. The airbag warning light is illuminated, and the steering-wheel controls and steering-wheel illumination are not functioning. The vehicle was involved in an accident in 2019; however, the engine ticking condition was already present before that accident, although it was less noticeable at that time. Despite previous repairs, the engine/valvetrain problem has returned. I am reporting this because the repeated camshaft/valvetrain failure, persistent cylinder #2 issue, possible timing-system problem, and associated risk of engine shutdown appear abnormal and potentially safety-related for a regularly maintained vehicle.

Filed Aug 28, 2026 · Fuel system · TX

Vehicle has a bad stumble/misfire under light load around 19 mph and 40 mph the vehicle lunges forward.After being at the dealership for over a month, They say it is normal operation that all their vehicles 3.6L.Being a mechanic for 30 years this is not normal operating conditions. I have researched this online as many Jeep owners complain about the same problem.

Filed Jul 13, 2026 · Engine, Fuel system · CA

I purchased this 2018 Jeep Wrangler JK Unlimited on July 19, 2025. Since purchasing the vehicle, I have experienced repeated mechanical failures that have required multiple repairs. The most serious issue involves the engine overheating at highway speeds without any visible coolant leak or clearly identifiable cause.Despite seeking professional diagnosis, the source of the overheating could not be determined. Shortly afterward, the vehicle developed a P0302 (Cylinder 2 Misfire), raising concerns about possible internal engine damage caused by the overheating.I believe this presents a significant safety hazard. An engine that overheats unexpectedly while driving at highway speeds can lose power or fail without warning, creating a dangerous situation for the driver and surrounding traffic. The vehicle has become unreliable and unsafe to operate because I cannot predict when it may overheat or experience another engine failure.As someone who often drives alone, I no longer feel safe taking this vehicle on long trips. I am concerned that the vehicle could leave me stranded on a highway or in a remote location without warning, placing my personal safety at risk. A vehicle should provide dependable transportation, not expose its occupants to the possibility of sudden mechanical failure.This vehicle has spent more time in repair facilities than on the road. I have incurred thousands of dollars in repair expenses, and I am now being asked to pay for an engine teardown simply to determine the cause of the failure before any warranty consideration can be made. Despite multiple repair attempts, the underlying cause of the overheating and engine problems has not been resolved.I am submitting this complaint because I believe the repeated overheating, unexplained engine malfunction, and resulting cylinder misfire may indicate a safety-related defect that warrants investigation. I request that the review to determine whether similar failure whether a broader safety issu

Filed Jul 7, 2026 · Engine · TX

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 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.

Filed Jun 29, 2026 · Engine, Transmission · VA

am the original owner of this 2015 Jeep Wrangler, which I purchased new. The vehicle has been properly maintained according to the manufacturer's recommended maintenance schedule. I have records documenting routine maintenance, including regular oil changes. At approximately 75,000 miles, I began hearing a persistent ticking noise from the engine. Because I was concerned that the noise could indicate a mechanical problem, I scheduled an inspection with an authorized Jeep dealership. The dealership diagnosed the vehicle with a failed rocker arm that caused damage to the exhaust camshaft. The dealership advised that the intake camshaft remained in good condition, indicating that the failure was isolated to the exhaust valvetrain at the time of diagnosis. This type of internal engine failure at approximately 80,000 miles was unexpected for a properly maintained vehicle. My concern is that if this condition is not diagnosed promptly, continued operation could result in further engine damage, loss of engine performance, engine misfire, or potential engine failure while the vehicle is being driven, creating a potential safety hazard. While researching this issue after receiving the diagnosis, I found numerous reports from other owners of vehicles equipped with the 3.6L Pentastar engine describing similar rocker arm and camshaft failures across Jeep owner forums, Reddit, Facebook owner groups, and YouTube. Although I understand there has not been a recall for this condition on my vehicle, I believe the number of similar owner reports suggests the issue may warrant further review. I am submitting this complaint so that the federal safety agency is aware of the issue and can evaluate whether similar failures are occurring with sufficient frequency to justify additional investigation.

Filed May 17, 2026 · Engine · NV

Engine - The vehicle is available but the engine was replaced. I was able to get home however there was a potential for significant engine failure. Yes it was inspected by an independent service center. Yes it was inspected by an independent service center. A check engine light came on. Upon further inspection it was a Cylinder 6 misfire P0306. When the engine was inspected further by a mechanic it was determined that the cylinder wall was damaged and that coolant had entered the cylinder. Due to the extent of the engine damage the engine needed to be replaced.

Filed Apr 20, 2026 · Engine · NC

On March 19, 2026 I paid $5,778.87 for repairs to my 2018 Wrangler JL. Repairs included the replacement of warped cylinder head and failed head gasket with coolant getting into the combustion chamber, showing up as rough running, misfire, flashing check engine light, and burning coolant smell. On April 18, 2026, at approximately 10:30 pm, after attending the [XXX] concert at Bank of America stadium (+70,000 in attendance), the vehicle stalled and was unable to be restarted or moved to the shoulder of the highway. The vehicle failure occurred on I277 outside of Bank of America Stadium with hundreds of cars passing us as my wife and were stranded in the middle lane. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)