GMC Yukon misfire problems

Filed Nov 2, 2026 · Engine, Fuel system · GA

During normal acceleration on the interstate entrance ramp, the vehicle stuttered and continued on seemingly without issue. Within a few minutes, I noticed the check engine light flashing and fluctuating oil pressure, and I drove cautiously to the closest mechanic shop a few miles away. The code (P0307) indicated a cylinder 7 misfire, and I was referred to the dealership for further diagnostics. The dealership determined the lifters failed resulting in damage to the camshaft, which they reported is a very common problem with the 5.3 L engine. The repairs were quoted in excess of $11,900. This sudden failure at highway speeds poses a safety risk to the motoring public. Furthermore, the consumer should not foot the bill for GM's manufacturing defects. This information is provided in the hopes that a recall is initiated.

Filed Oct 20, 2026 · Engine, Transmission · PA

VEHICLE: 2021 GMC Yukon, 5.3L V8 (L84). VIN: [XXX]. Mileage at failure: approximately 88,000. Component: Engine. INCIDENT DATE: XXX While I was driving on a highway, the engine began to misfire and I heard a ticking noise. The check engine light then began flashing, indicating a severe misfire. I pulled off the highway immediately to a rest area. The vehicle was towed to a GMC dealer. The dealer's diagnosis suspected failed valve lifters, and the repair orders call for a misfire diagnosis with the Bank 1 cylinder head removed, and replacement of the camshaft, lifters, and related parts. This failure caused sudden loss of engine performance at highway speed. The engine began smoking. My family and I were in the vehicle, and we were fortunate there was a safe place to stop. I believe this is a known defect. GM Service Bulletin PIP5776, "Misfire Due to Collapsed Lifter," covers 2021 GMC Yukons with the 5.3L L84 engine. It describes a misfire with a bent pushrod leading to a collapsed lifter or a lifter that comes apart, and it attributes the cause to an internal lifter concern. Many other owners of GM V8 trucks and SUVs have reported the same failure, and a class action over the AFM/DFM lifters has been pending against GM in federal court in [XXX] since 2021. I bought this vehicle new and have maintained it. This is the second time this vehicle has left my family stranded on a highway. In 2024, a separate known issue left us, including three children under [XXX], on the side of a major highway about 7 hours from home. GM repaired that issue. For the current failure, GM has not agreed to cover the repair. It has offered $5,951.39 toward an engine replacement, which would leave me responsible for $13,886.59 plus teardown labor. I am filing this complaint so the federal safety agency is aware of this failure, which can cause sudden loss of power on the highway. GM case number: XXX. Dealer: Fred Beans Buick GMC, [XXX]. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Sep 30, 2026 · Brakes · MO

Abs system is not functioning properly, codes are being thrown for multiple things such as cylinder 2, which all spark plugs and coils and spark lines were fixed, then it ran for one day and threw a different code of cylinder 6 misfire with the abs and stailitrx system not functioning correctly. Several parts have been changed on this by professionals and they can’t figure out why this is happening. I don’t have my full hp.

Filed Sep 22, 2026 · Engine · WA

The vehicle developed a recurring cylinder #4 misfire with a flashing check-engine light, rough running, and reduced performance. Diagnostic code P0304 repeatedly returned. Replacing the #4 spark plug temporarily restored normal operation, but the misfire returned after a few hundred miles. The #4 plug was wet/oily, and fresh oil was found pooled in the #4 intake port while the other ports were dry. All eight spark plugs, ignition coils, and plug wires were replaced, along with the #4 fuel injector and both #4 valve-stem seals, but the misfire persisted. A valvetrain/lifter tick later became audible near 3,000 RPM. The failure has now been confirmed as a valvetrain failure that severely damaged/destroyed cylinder #4 and requires complete engine replacement. The vehicle is available for inspection upon request. This defect creates a serious risk of severe misfire, loss of engine performance, or complete engine failure while driving.

Filed Sep 3, 2026 · Engine · MS

My 2021 GMC Yukon began experiencing severe engine problems, including shaking/rough running, a noticeable ticking/knocking noise from the engine, and a flashing check-engine light. The vehicle also displayed Service ESC and traction control warnings and exhibited symptoms of an engine misfire. I took the vehicle to a dealership for evaluation. I was advised that the problem may involve failed lifters and that the vehicle could be out of service for several weeks for repairs. I was also advised that the repair could be very costly. At this time, I have not been given a final diagnosis, so the exact internal engine component responsible for the failure is UNKNOWN. I am concerned that the condition presents a safety risk because the engine is running extremely rough and the check-engine light is flashing. I am afraid the engine could lose power or fail while the vehicle is being driven, potentially putting me, my passengers, and other motorists at risk. I have also become aware of the federal safety agency's investigation involving failures of the 6.2-liter L87 V8 engine in GM vehicles, including the GMC Yukon, as well as reports of engine failures occurring after certain repairs or recall remedies. This has increased my concern about whether repairing or replacing individual engine components will permanently resolve the problem. I am submitting this complaint so that my vehicle's symptoms, dealer evaluation, and potential engine failure are documented. The vehicle and affected components are available for inspection upon request. The dealership has evaluated the vehicle, but a final determination of the exact cause has not yet been provided.

Filed Sep 1, 2026 · Engine · TX

My 2021 GMC Yukon Denali with approximately 88,000 miles developed a significant engine knocking noise and was towed to a GMC dealership for diagnosis. The dealership confirmed diagnostic trouble code P0301 (engine misfire) and documented a “knocking noise in lower end at piston rod crankshaft area.” The dealership advised that my vehicle is not currently included in the existing GM recall for certain 6.2L L87 engines. The vehicle has the 6.2L L87 V8 engine. I am concerned because the documented knocking is located in the lower engine area involving the piston/connecting rod/crankshaft area, which is consistent with the type of internal engine failure associated with the L87 engine investigation and recall. I am concerned about the possibility of sudden engine failure and loss of propulsion while driving. I am requesting that the federal safety agency investigate this failure and consider whether vehicles outside the current recall population should also be included. I also recently experienced an engine replacement on another 2024 GMC vehicle. I am providing that information as additional customer experience, but I am not claiming that the two failures are necessarily caused by the same defect.

Filed Aug 30, 2026 · Engine · TX

The engine issue was caused by a misfire in cylinder #5, which resulted in white smoke coming from the vehicle’s exhaust. While driving on the highway, the vehicle lost power and would not accelerate properly, creating a serious safety hazard due to the inability to maintain speed and safely respond to traffic conditions.

Filed Aug 30, 2026 · Engine · TX

The engine issue was caused by a misfire in cylinder #5, which resulted in white smoke coming from the vehicle’s exhaust. While driving on the highway, the vehicle lost power and would not accelerate properly, creating a serious safety hazard due to the inability to maintain speed and safely respond to traffic conditions.

Filed Aug 30, 2026 · Engine · TX

The engine issue was caused by a misfire in cylinder #5, which resulted in white smoke coming from the vehicle’s exhaust. While driving on the highway, the vehicle lost power and would not accelerate properly, creating a serious safety hazard due to the inability to maintain speed and safely respond to traffic conditions.

Filed Aug 29, 2026 · Transmission · NY

My vehicle previously experienced engine problems severe enough that the engine was replaced. Despite the engine replacement, the vehicle is continuing to experience an engine misfire, and the check-engine light has been flashing. A flashing check-engine light and active misfire are a serious safety concern because the vehicle may experience rough running, reduced power, hesitation, or potential loss of power while driving. The fact that the misfire continues after an engine replacement raises concerns that the underlying problem was not resolved or that another component or system is malfunctioning. The exact cause of the current misfire is UNKNOWN at this time. The vehicle and/or affected components are available for inspection upon request.