2012 Jeep Wrangler: check engine light

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 Apr 1, 2026 · Engine · 71,756 miles · NY

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.

Filed Oct 15, 2024 · Brakes, Driver assistance · 55,000 miles · TX

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.

Filed Apr 4, 2023 · Engine, Fuel system · VA

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.

Filed Dec 7, 2022 · Engine · UT

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

Filed Nov 17, 2022 · Engine · 60,000 miles · TX

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 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.

Filed May 2, 2022 · Electrical, Engine · WI

Random Stalling while driving, making a left-hand turn. While entering an intersection, the vehicle stalled losing all power. Was able to coast to a safe spot. Waited 15 min, the vehicle started. No check engine light.

Filed Jun 11, 2021 · Engine · 90,000 miles · CT

The contact owns a 2012 Jeep Wrangler. The contact stated that the engine would misfire while driving at various speeds. Due to the failure, the vehicle would independently go into limp mode with the traction control and check engine warning lights illuminated. The contact had taken the vehicle to several unknown dealers and the engine misfire was acknowledged however, the cause of the failure was not determined. The manufacturer was not notified of the failure. The vehicle was not repaired. The failure mileage was approximately 90,000. The VIN was not available.

Filed Oct 5, 2020 · Engine · 30,000 miles · TX

While driving engine looses power and vibrates excessively, engine light flashes during this process, after about 30 seconds light goes out and engine resumes normal operation. It has done this multiple times sometimes on startup sometimes stopped at a light and other while driving.

Filed Oct 1, 2020 · Fuel system · 5 miles · CA

Sudden acceleration with brakes not responding .this has happened 4 times and only way was to pull out of road and jam brakes and disengage from drive to park in a moment to avoid accidents or me driving of the side road . This was reported to dealership and nothing came back with no check engine light on. I always done my service at dealership and apparently supposedly nothing has been reported of this nature.it feels like it's on cruise control with having a speed of it's own but brakes are not responding normally. Hopefully can address asap lucky I've been working from home but I shouldn't be afraid to drive my own car. This is a very serious safety issue and needs attention asap.thanks mb

Filed Sep 12, 2020 · Electrical, Engine · 118,000 miles · CA

My jeep will randomly just shut off while idling in a parking lot or stopped at a ligh. If I turn the key it will start right back up. No check engine lights or codes. I have had it to a mechanic and they can't figure out what is wrong .

Filed Mar 18, 2020 · Acceleration, Engine · 67,800 miles · CA

Beginning of feb., lost power on freeway. Went from 65 to 40 MPH and could not accelerate. Engine and traction lights came on. Exited the fwy and drove to dealer where I was turned away due to high volume. Left my jeep at the dealer the following day with this issue and to correct campaign #v51 recall. The engine light wasn't lit anymore and dealer couldn't find anything wrong with it so I picked it up. Couple of weeks later, I failed the smog check I need to register my jeep, and an engine code showed up, p0394. I took it to other places where the same code showed up and was recommended to take it back to the dealer. Going downhill, my father experienced the same while driving my jeep. Beginning of march, omw to the dealer on the fwy, I lost power again and the engine and traction lights came on. I showed the dashboard to the service advisor, explained the continued problem and the code showing up. I left my jeep there for several days because they couldn't reproduce the problem and didn't know what was causing it. The code was cleared when I picked it up. The following day, as I was making a right turn into a parking lot, the engine stalled. I used gravity to partly move back down as there was another car driving into the lot. I put it on "park" and I was able to restart the car. No engine light this time. This morning I lost power driving to the first stop on my street (stop on my side only). I had already entered the t-intersection but could not accelerate to turn left. I put it in "park" then back to "drive" and accelerated normally. There were no cars around because of the corona virus, but I would have been hit on the driver's side if a coming vehicle (who has the right-a-way), decided not to slow down.