2021 Jeep Grand Cherokee: misfire or rough idle

Filed Nov 5, 2026 · Engine · NJ

September 1: The vehicle triggered diagnostic trouble code P0306 (Cylinder 6 Misfire). It was immediately taken to an independent mechanic where the spark plugs were replaced to address the misfire. September 30: The engine suddenly refused to crank or start. The vehicle was towed back to the independent mechanic. The technician diagnosed a completely blown starter motor and noted thick white smoke billowing from the tailpipe upon replacement. Further testing revealed that engine coolant had flooded into Cylinder 6. Present: The vehicle was towed to an authorized Jeep Dealership for a comprehensive engine teardown. The dealership technicians confirmed that both the cylinder head and the engine block deck are permanently warped due to extreme localized thermal stress. Dealership advised coolant was not low and no codes on the computer to show that there was overheating occurring. All oil changes were done at the dealership and stellantis don't want to help with the replacement of the engine goodwill offered 10,500 digital imaging says no my fault I drove it overheating Coolant not low per dealership and no lights how was I to know it was overheating

Filed Oct 12, 2026 · Electrical, Fuel system · PA

Vehicle: 2021 Jeep Grand Cherokee Overland, 3.6L V6 Incident Date: [XXX] Location: [XXX] Safety Complaint: On [XXX], while driving my 2021 Jeep Grand Cherokee Overland on [XXX], the vehicle suddenly lost accelerator response while traveling on the highway. The engine initially remained running, but pressing the accelerator pedal produced no response. Multiple warning indicators illuminated simultaneously, including the electronic throttle control, ABS, traction control, airbag, and four-wheel-drive systems. The vehicle also exhibited unusual electrical behavior, including unexpected activation of the high-beam headlights. The vehicle subsequently became completely inoperable and would no longer crank or start. The sudden loss of propulsion while traveling in highway traffic created a serious safety hazard and placed me at risk of a collision. This incident follows an extensive history of significant mechanical failures and repairs to this vehicle, including: Replacement of the cylinder head following repeated overheating and engine misfires. Complete transmission replacement following transmission-related failures. Replacement of the radiator and cooling fan assembly TWICE within approximately one year, most recently during a trip to North Carolina. Additional mechanical concerns, including a camshaft-related diagnostic trouble code. Despite these major component replacements, the vehicle continues to experience serious reliability and operational failures. These repeated problems have occurred despite attempts to address them through dealership repairs and manufacturer warranty assistance. Stellantis previously extended the vehicle's warranty as a goodwill gesture following earlier issues. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Apr 2, 2026 · Electrical, Engine · PA

This submission is an update to the federal safety agency Complaint #11727024. The vehicle continues to experience recurring engine overheating and misfire conditions. These issues have been previously diagnosed and are consistent with known manufacturer Technical Service Bulletins (TSBs) related to this engine. Despite this: The dealership has not performed the appropriate diagnostic protocol (including STAR testing) The manufacturer, Stellantis, closed my case without resolving the issue No repair or corrective action has been completed The vehicle remains in operation due to lack of manufacturer support. This condition presents a potential safety risk, including: Loss of power while driving Risk of engine failure or shutdown Increased risk during normal roadway operation The vehicle is regularly operated by my 17-year-old daughter, which increases concern regarding driver safety and reliability of the vehicle under these conditions. This situation reflects: A known defect documented by the manufacturer Failure of the dealer network to properly diagnose/repair Closure of a manufacturer case without resolution of a safety-related issue I am requesting that this complaint be reviewed as part of any broader pattern of similar failures and considered for further investigation.

Filed Mar 25, 2026 · Electrical, Engine · PA

I am reporting a repeated safety-related issue involving my 2021 Jeep Cherokee Overland. The vehicle has experienced ongoing engine misfires and overheating, which create unsafe driving conditions. The issue presents as follows: -Engine begins to misfire, causing rough operation and shaking. -The check engine light flashes intermittently indicating active misfire. -Vehicle performance becomes inconsistent, with concern for loss of power while driving. -Vehicle experiencing coolant loss/overheating, concern for engine failure. These conditions create a serious safety risk, as the vehicle may lose power unexpectedly or become inoperable while driving. Multiple repair attempts have been made, including replacement of ignition components (coils and spark plugs) and other related service. The issue continues to recur, and the root cause has not been resolved. Despite repeated attempts to resolve the issue through the dealership and manufacturer, the problem persists and the vehicle remains unreliable. The manufacturer has not provided a resolution despite multiple attempts, and communication is unsuccessful I am submitting this complaint due to ongoing safety concerns and a lack of resolution.

Filed Mar 17, 2026 · Fuel system · AL

Fuel pump loosing prime it cracks either in housing or hose internal to the tank and it causes it to loose prime. Long Crank Times/No Start And stall and rough idling at stoplights and upon acceleration. Issue was confirmed and reproduced by independent service center.

Filed Mar 3, 2024 · Engine, Fuel system · IL

It has been observed that the antifreeze and oil are intermixing in the antifreeze reservoir, causing the check engine light to illuminate and the system to register a code of PC304. This particular code is indicative of a cylinder misfire, which can cause the car to stop functioning properly and eventually lead to potential engine damage. To resolve this issue, it is imperative to replace the oil cooler filter adapter and flush the engine. This will ensure that the antifreeze and oil are no longer mixing and the engine is functioning efficiently. Therefore, it is highly recommended to take immediate action and get the necessary repairs done to avoid any further damage to the engine.

Filed Dec 3, 2020 · Engine · 500 miles · MA

Tl* the contact owns a 2021 jeep grand cherokee. The contact stated that while driving approximately 30-45 MPH, the transmission felt as if it was slipping. There was no warning light illuminated. The contact pulled over to the side of the road and turned off the vehicle. The vehicle was towed to imperial cars (8-18 uxbridge rd, mendon, ma 01756; (800) 526-2886) to be diagnosed. The contact was informed of several cylinder misfires. The contact was informed that the engine needed to be replaced. The repair was still pending. The manufacturer was made aware of the failure and a case was filed. The approximate failure mileage was 500.