GMC Complaints

On [XXX], I was driving on the highway with my family in the vehicle and the check engine light came on, then it started running roughly. I headed off the highway on an exit ramp and the engine died about halfway down the ramp. It wouldn't restart after that. This happened about an hour away from my house in Painesville, OH. I live in Erie, PA. I had to tow it to the nearest GMC dealer. They've since concluded that the engine failed and have ordered a replacement engine from GMC. The yukon only had about 4,900 miles on it. GMC has claimed that their engine problems were fixed for the 2025 and 2026 model years, or else I would not have purchased this vehicle. Obviously there are still major issues and the 2026 6.2L engines need to be recalled. I understand that there is an ongoing investigation into these issues: RQ26001. Please see that the investigators are made aware of this incident. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I am submitting this complaint to report a safety defect involving a 2026 GMC Yukon XL AT4 equipped with the GM Brembo brake upgrade. The vehicle is sold as equipped with a full-size spare tire; however, the spare tire/wheel supplied cannot be mounted due to interference from the brake calipers. This incompatibility was discovered only after a flat tire event on [XXX], during which the vehicle could not be safely returned to service. The Brembo brake upgrade is a GM-designed option that is installed by the dealer in all cases. Despite this, the vehicle was delivered with emergency equipment that is unusable in the event of a flat tire. GM has acknowledged the incompatibility and relies on a warning label placed beneath the vehicle, rather than providing a compatible spare or disclosure at the point of sale. This defect resulted in a prolonged roadside emergency involving an elderly passenger and a failure of manufacturer-provided roadside assistance. I believe this condition affects all vehicles equipped with the Brembo brake upgrade and represents a systemic safety issue involving emergency preparedness and disclosure. Supporting documentation and a detailed incident narrative are available upon request. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The 3.0L diesel motor failed around 5700 miles. The thrust bearing failed and the engine and the turbo needed to be replaced.

Warning message appeared stating "service brake assist" and "service ESC". Took vehicle to dealer, they found faulty Master Cylinder. Multiple parts involved, some on back order, could take weeks to a month or more for repair. Vehicle is less than 1 year in service with approx. 6k miles.

Purchased brand new vehicle 2026 XL Denali, hadn’t even had my first oil change, and had a complete engine failure in the middle of the road. Prior to engine failure, car ran fine without an issue - so failure came out of nowhere. Towed, where GMC and dealer determined entire engine needed to be replaced. GMC did cover and dealer did install a new engine. However: 1. I was out of a vehicle for almost a month. 2. I have incurred a depreciation cost of 10-15% on my vehicle due to this problem. 3. I have lost confidence in my brand new vehicle, as GMC has not fixed the reoccurring engine problems from previous years - despite promises to the contrary.

On 12/22/2025 I took my 2023 GMC Yukon in for the L87 recall. After receiving information that my vehicle passed the recall they told me that the oil would be change to from OW-20 to OW-40 and that my oil changes would go up in price (double the price) due to the oil being a high performance oil. On 01/05/26 exactly two weeks and 616 miles later our engine and lights completely stopped working while driving it on the road!!! The vehicle would not start or switch into neutral so we could get the vehicle off the road due to blocking traffic! The vehicle was towed the GMC dealership and had to have a new engine replacement. We were out of our vehicle for 31 days. Now our vehicle rear view camera guidelines have stopped working and now have to put that under warranty claim.

Automatic emergency braking system deployed unexpectedly on acceleration from a traffic light stop. Vehicle was about 10-15 MPH and system operated with no brake pedal input. A vehicle behind had to do a panic stop to avoid collision. Deployment disengaged when accelerator pedal was released. My wife, principal driver, was in the car. She advised this had occurred two times before. No recalls are presently listed for the vehicle.

The contact owns a 2021 GMC Acadia. The contact stated while driving at an undisclosed speed, the check engine warning light illuminated and DTC: P04FB; was displayed. The vehicle was taken to the dealer where it was diagnosed with moisture of the crank case. The vehicle was repaired. The contact stated that the failure was a quick fix and was covered under the warranty. The contact stated that the failure had occurred several times and was covered under warranty. The contact was informed that there was no fix for the failure. The manufacturer was not made aware of the failure. The failure mileage was approximately 37,000.

The contact owns a 2025 GMC Terrain. The contact stated that while his wife was driving approximately 40 MPH on wet roads, the brake pedal was depressed, but the brake pedal was stiff, preventing the vehicle from slowing down as intended. There were several unknown warning lights illuminated during the failure. The accelerator pedal was released, and the vehicle rolled to a stop. The vehicle was turned off and restarted, but the check engine warning light remained illuminated. The vehicle was pulled over to the side of the road and turned off. The vehicle was then towed to a dealer, where it was diagnosed, and determined that the brake control module needed to be replaced. The vehicle was repaired, but the failure reoccurred approximately 7 months and 2 weeks later. The manufacturer was notified of the failure. The failure mileage was approximately 1,126.

The contact owns a 2026 GMC Sierra 1500. The contact stated that while driving at an undisclosed speed, the vehicle made an abnormal sound and failed to accelerate as needed. There was no warning light illuminated. The vehicle was taken to the dealer, who determined that the engine needed to be replaced. The vehicle was not repaired and remained with the dealer. The manufacturer was not made aware of the failure. The failure mileage was approximately 6,000.