2018 Jeep Wrangler: misfire or rough idle

Filed Sep 18, 2026 · Engine · SC

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

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 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)

Filed Apr 19, 2026 · Engine · WI

I have a 2018 Jeep Wrangler JL Sport S (2 door) with approximately 66,000 miles. On March 26th, 2026 I had a flashing check engine light come up along with the vehicle shaking in low gears. I had the vehicle towed to the Jeep dealership (Gandrud Auto Group) from which I bought it from and upon their inspection they found the left bank head gasket leaking coolant into the combustion chamber causing misfires. This repair was over $5000 and took over a week to fix. The service ticket from Grandrud will be attached which lists all parts that needed to be replaced. This vehicle is much too new to be having these kinds of issues and Gandrud even stated that many customers with JL Wranglers have been coming to them with the same issue of the head gasket failing. 1. Left bank head gasket leaking coolant into the combustion chamber causing misfires. Photos will be attached. 2. Shaking vehicle. Had vehicle towed. 3. Dealership inspected and identified the issue. Invoice attached. 4. Check engine light came on for just one day back in December of 2025, was brought into Gandrud and it was a misfire code, no noticeable issues at the time however and check engine light went away. On March 26th, 2026 I had a flashing check engine light come up along with the vehicle shaking in low gears.

Filed Jan 29, 2026 · Engine, Transmission · FL

Vehicle equipped with a 3.6L Pentastar V6 engine developed loud ticking noises, engine misfires, and loss of power while driving. The vehicle hesitated during acceleration and could not reliably maintain speed, creating a safety risk in traffic. An authorized dealership pulled diagnostic trouble codes, acknowledged the abnormal ticking, and advised the failure was likely related to the camshaft, lifters, and rocker arms. The vehicle was then taken to an independent mechanic for further inspection. The independent mechanic confirmed failure of the valve train and camshaft components, requiring replacement of the passenger side intake camshaft (Bank 2), cam phaser, phaser bolt, and all lifters and rocker arms. Photos of the failed components are available. The defect was confirmed by both a dealership and an independent repair facility. Issue presents risk of sudden loss of power while the vehicle is in motion.

Filed Jan 15, 2026 · Engine · MD

On January 14, 2026, my 2018 Jeep Wrangler JK Sport (3.6L) with approximately 134,099 miles was inspected at Cox’s Automotive & Repair Inc. due to a check engine light and rough engine operation. During diagnostic testing, multiple fault codes were identified, including P000A (camshaft position slow response), P0300 In addition to the diagnostic findings, I contacted and visited multiple automotive repair facilities regarding this issue. Each shop advised that they have previously serviced 2018 Jeep Wrangler JK models with the same 3.6L engine presenting identical symptoms and diagnostic codes, including timing correlation errors, misfires, and internal engine damage. Several repair facilities indicated that they have had the same make and model in their shops for the same failure, including vehicles with significantly lower mileage, with one reported case occurring at approximately 7,000 miles. Based on consistent feedback from multiple independent repair facilities, this condition appears to be a known and recurring mechanical issue associated with this vehicle model, rather than damage caused by misuse, neglect, or owner fault. (random/multiple cylinder misfires), P0017 and P0019 (camshaft/crankshaft timing correlation errors). Upon removal of the oil filter, metal debris was found in the oil filter cartridge, indicating possible internal engine damage. Based on these findings, the repair facility recommended engine replacement or major engine repair.

Filed Dec 2, 2025 · Engine · CO

Started having misfire issues. Replaced spark plugs. problem continued. started having to add antifreeze regurlarly. 1 quart per 300 miles. multiple P0302 error codes. Dealer 1st tried to tell me was a loose coil pack. looked at it again and said needs a new head gasket possibly a whole new engine. 117,000 miles and this seems rediculous for a 60,000 dollar vehecle. Especially since Jeep already issued an extended 150,000 mile warranty for 2011-2013. with 100's of these same issues still happening on 2018's and latter they clearly did not correct the defect.

Filed Oct 23, 2025 · Engine · NC

The Check Engine light illuminated and diagnostic code P219A was recorded (Bank 1 Air/Fuel Ratio Imbalance), and the engine has a ticking noise. The dealership has indicated the issue likely involves the valvetrain/rocker arms/lifters and will require engine internal repair (valve cover removal, spark plug replacement, possible rocker arm replacement) estimated at ~$2,900-$4,500. The 3.6 L Pentastar engine has been the subject of numerous owner complaints of ticking noise, power loss, misfire, and premature valvetrain failure. I understand there have been related Jeep Technical Service Bulletins (such as 09-002-14 and 09-008-18) addressing these types of failures. A class action lawsuit (Maugain et al. v. FCA US LLC) alleges defects in the 3.6L Pentastar engine’s valve train (rocker arms, lifters) and failure to disclose the defect. Maintenance History: Regular oil changes (every <6,000 miles) at approved service centers; no prior major engine internal repairs. Concern: The defect affects engine performance, may lead to catastrophic engine failure, and potentially reduces safe vehicle operation and control (power loss, hesitation). Relief Sought: I request the federal safety agency open a vehicle safety defect investigation and compel FCA / Chrysler / Jeep to evaluate this condition under recall criteria.

Filed Oct 23, 2025 · Engine · CA

My Jeep began misfiring, giving a P0304 error code via the ODB. On June 2nd 2025, we took it to the Sandy Sansing CDJR Dealership. They determined that my 3.6L Pentastar V6 engine needed a new camshaft and lifters, despite having only 42,609 miles on it. To further complicate things, it took the dealership over a month to get a replacement camshaft in and installed, due to an abnormally high demand for replacement camshafts; this suggests a systemic problem with the engine, especially considering the problematic history of earlier versions of the 3.6L Pentastar V6 (1).

Filed Sep 22, 2025 · Engine, Fuel system · IL

My 2018 Jeep Wrangler JL Sport is experiencing multiple premature engine failures that present a serious safety risk: •Vehicle overheats while driving. •Recurrent misfire on Cylinder #5 (DTC P0305). •White exhaust smoke with a sweet coolant smell on cold start. •Coolant loss despite recent refill. •Oil contamination with metallic particles found during inspection. •Valvetrain noise from the right bank, suspected intake camshaft wear. These conditions create a risk of engine seizure or sudden stalling while driving, which could cause a crash. Manufacturer awareness: Jeep/Mopar has issued bulletins acknowledging these exact problems, including: •TSB MC-11018482-0001 (May 2025): Intake camshaft/rocker wear causing misfires (P0301–P0306). •Customer Satisfaction Notification ZD8 (2023): Coolant inlet tube fastener issue causing coolant leaks and overheating. My vehicle’s symptoms directly align with these known manufacturer issues. Despite this, Jeep/Mopar has denied goodwill repair coverage. Safety Concern: This defect is not just a performance issue — it creates a high probability of sudden engine stall or seizure, endangering me, my passengers, and other drivers. I am requesting the federal safety agency investigate premature engine failures on the Jeep Wrangler JL (3.6L Pentastar) and require Jeep/Mopar (Stellantis) to address this safety hazard.

Filed Sep 16, 2024 · Engine · MI

The 3.6l v6 (mostly in the 2014-2020 wrangler) has a known issue for cylinder 4, 5 and 6 misfires, warping, metal shavings, damaged cams, ticking, overheating etc. My wrangler has had this issue multiple times and the cost to repair it is well over $4000 each time. The first time, my wrangler had 85000 miles and now it has 135,000 miles. The vehicle overheats, starts rough, idles rough, loses power, mpg tanks and its a huge safety issue (I drive my 2 year old son around a lot, as well as my dog).