GMC Complaints

The contact owns a 2026 GMC Sierra 1500. The contact stated that intermittently there was no sound while the turn signals were activated, and the radio and incoming calls failed to be audible. The issue often lasted all day or for an hour or two before returning to normal. The contact associated the failure GM Technical Service Bulletin: PIT6406 (or PIT6406F), but the dealer stated the vehicle was not included in the bulletin and refused further diagnostic tests. The vehicle was taken to a dealer to reprogram the Audio Control Module (ACM) because the software was outdated, despite the vehicle being brand new. The reprogramming was completed; however, the failure was not resolved. The manufacturer was notified of the issue. The failure mileage was 3,657.

The contact owns a 2016 GMC Yukon. The contact stated that while driving at an undisclosed speed, the brake pedal was depressed; however, the vehicle failed to stop as intended. The contact stated that there was an abnormal sound coming from the vehicle and the ABS warning light was illuminated. The contact stated that after several attempts, the vehicle stopped. The vehicle was taken to the dealer; however, the vehicle was waiting to be inspected. The contact stated that an unknown recall repair with a similar description was completed in 2024; however, the contact was informed that the repair was not covered under warranty. The manufacturer was made aware of the failure but provided no assistance. The failure mileage was approximately 136,000.

I purchased my 2020 GMC Sierra 1500 AT4 with the L87 6.2L V8 new from a GMC dealer in March 2020 for $65,910 (VIN [XXX]). The truck has primarily highway mileage, very little towing, and has been well maintained. At 166,634 miles on [XXX], the truck developed a flashing check-engine light. The GMC dealer diagnosed “Cyl 3 lifter failure with camshaft damage” and determined that replacing the engine was preferable to repairing it because of the vehicle's mileage. The dealer installed a replacement OEM GMC engine and replaced both broken engine mounts. The replacement engine and installation cost $11,778. The replacement engine has subsequently required multiple repairs. At approximately 170,411 miles, the GMC dealer documented an exhaust leak that had occurred since the engine repair and a coolant leak from the upper radiator hose; both were repaired. At approximately 187,699 miles, the truck experienced overheating, coolant leakage, and loud engine-area noise. The dealer found that the water pump was coming apart and replaced the water pump and related components. I am reporting this vehicle because it is a 2020 Sierra equipped with the L87 6.2L engine and experienced catastrophic lifter/camshaft failure requiring complete engine replacement, followed by multiple engine-related repairs. I believe this history is relevant to NHTSA's investigation of L87 engine failures in earlier model years and warrants consideration when evaluating whether the known L87 engine defect extends beyond the vehicles currently covered by the recall. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

On August 22, 2026, I was driving my 2023 GMC Yukon Denali with the 6.2L V8 at highway speed when the vehicle began struggling to maintain power while climbing a hill. The engine then developed a noticeable knocking sound. Shortly afterward, the engine shut off completely while the vehicle was moving, causing a sudden loss of propulsion. I was able to bring the vehicle to a stop, but the engine would not restart. The electronic transmission also would not shift into Neutral and displayed a message indicating that the conditions required to shift were not met. Because the vehicle could not be shifted out of Park, the towing company had difficulty loading and unloading the vehicle. The failure occurred during normal highway driving and created a significant safety concern because the engine shut down without warning while the vehicle was in motion. I am aware of NHTSA Recall 25V-274 / GM Recall N252494000 involving certain GM vehicles equipped with the 6.2L L87 engine, as well as NHTSA Engineering Analysis EA25-007 concerning engine failures and loss of propulsion. At the time of this complaint, the dealership has not yet confirmed the specific mechanical cause of my vehicle’s failure. The vehicle is being taken to an authorized GMC dealership for diagnosis. I am submitting this complaint because of the sudden engine failure and loss of propulsion while traveling on a highway.

Cruise control activates at speeds between 1-5mph, which frequently happens while turning, parking, or going through a drive-through. The cruise control activates by a toggle on the left spoke of the steering wheel, which can be easily bumped while doing low-speed maneuvers like parking. When bumping the toggle, the cruise indicator shows a set speed of 15-18 mph, and the vehicle surges forward trying to attain that speed. Since this occurs while maneuvering to park, it creates a dangerous situation if anyone is nearby and you are unable to react in time. This is an ongoing problem that can be duplicated at will. Rear backup camera very dark at night it’s unusable.

Engine failed. Had to be towed to the dealer to get a new motor. It was part of the 6.2l L87 recall

We just purchased our Yukon from a dealership in February (2/7/26) and it was diagnosed with premature failure of at least one AFM valve lifter as it is causing engine misfires, shaking and stalling on 7/30/26. We just hit 67,000 miles on the odometer so we are just beyond the warranty coverage. The lifters were replaced previously by the previous owners on 12/16/24.

While we were visiting Canada, our GMC Yukon had fewer than 5,000 miles when its engine seized on the highway. The vehicle was taken to a GMC dealership in Canada. The dealer advised that the engine needed to be replaced, and it has now been replaced. We need to back to Canada to pick up the vehicle.

On [XXX], while driving my 2025 GMC Sierra 1500, VIN [XXX], near [XXX], California, the vehicle suddenly experienced a severe brake failure while traveling on a public roadway. When I attempted to apply the brake pedal, the vehicle failed to brake normally and I was unable to safely stop the truck using normal braking. I was forced to reduce speed and allow the vehicle to coast until I was able to enter a side road and bring the vehicle to a stop. I was extremely fortunate that traffic conditions were light at the time. A vehicle traveling in front of me, an intersection, pedestrians, or heavier traffic could have resulted in a serious or fatal crash. After stopping the vehicle, I discovered a metal retaining ring/clip on the floor directly underneath the brake pedal area. At approximately the same time, multiple brake system failure and warning indicators illuminated on the instrument panel. I immediately contacted GMC through the vehicle's SOS system and reported the brake failure. The vehicle was subsequently towed and delivered to a GMC dealership/service department for diagnosis and repair. This appears to involve the mechanical separation or detachment of a component associated with the brake pedal assembly. I have retained the metal component, video evidence of the condition and warning lights, towing information, and dealership repair documentation. A sudden loss of braking caused by the separation of a brake pedal component presents an immediate and potentially life-threatening safety risk. I respectfully request that NHTSA investigate this failure and determine whether similar failures have occurred in other 2025 GMC Sierra 1500 vehicles. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

2015 gmc Acadia, vin ending 7457,p2635,stuttering/hesitation and engine stalling when Arizona temperatures exceed 100* f , and mechanic advising that the condition corresponded to a known gmc issue for which they could not obtain an applicable corrective part / repair