GMC Complaints

Vehicle would slowly roll even when break is applied. It was confirmed by the service center that the break booster vacuum pump was only reading 8 when it should be at 27. It was not making enough pressure. The vehicle would not stop when break was applied.

On a long trip the fuel tank straps and bolts holding the gas tank failed causing the fuel tank to fall and be dragged causing massive fuel spill. The problem has been confirmed by the dealer. The part was not inspected by police. However, we did get pictures of the tank at the scene. No warning lanmps or sfty signals were

Burning oil too much too fast oil all over motor and engine and white smoke inside the car all records are with GMC DEALER

The contact owns a 2022 GMC Sierra 3500. The contact stated that the rear windshield frame was cracked, which allowed water to leak into the vehicle. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was made aware of the failure. The failure mileage was approximately 29,000.

On June 25, 2026, at approximately 84,000 miles, while traveling approximately 60-65 mph on Highway 121 in a posted 65 mph zone, driving my 2021 GMC Sierra 1500 AT4 equipped with the 6.2L L87 engine, multiple warning messages suddenly appeared, including “Check ESC,” “Check Parking Brake,” “Check Brakes,” and “Check Engine.” The engine began operating abnormally. I drove directly to Sewell GMC because I was concerned that the engine could fail or the vehicle could lose propulsion while in traffic. There was no crash, fire, or injury. Sewell GMC inspected the vehicle and confirmed catastrophic internal engine damage. The technician found metal debris in the engine oil and oil pan, damaged internal bearings, and camshaft/lifter damage. Sewell advised that the complete engine must be replaced. The vehicle remains at the dealership, has not yet been repaired, and the engine and failed components should be available for inspection. Before this incident, I had not experienced warning lights or symptoms indicating that an imminent catastrophic engine failure would occur. GM and the dealership advised that my VIN is not included in the current L87 engine recall because the engine was built in 2020. However, the diagnosed bearing damage, metal contamination, and catastrophic engine failure appear similar to the engine failures addressed by that recall. I am reporting this because an unexpected internal engine failure while driving creates a serious risk of loss of propulsion and a collision.

My vehicle a 2016 GMC Sierra 1500 upon lower idle speeds loses vacuum pressure. As the vacuum level drops the brake assist decreases, increasing the braking effort, extending the distance required to stop the vehicle, which increases the risk of a crash. I have had a warning light come on advising to service the brake assist system. I took my truck to a local mechanic who confirmed the codes and learned that there had been a GM recall associated with this failure at one time, with GM recall # N192268490. There is also NHTSA recall bulletin 19V645000 regarding this matter as well. Upon contacting some local GM dealers in the area, I was informed that my VIN was not listed as one of the vehicles affected by this recall, so a recall notice was never sent regarding my vehicle. I was also told that I just fell outside their 10-year window regarding this matter and that they would not repair this safety issue under warranty. I called the GM customer service who could not explain why the VIN associated to my truck was not listed and they said I should contact NHTSA and start a claim for potential reimbursement in the future after repairs are made. I feel that this is an unnecessary step as I believe GM should honor their product and repair an obvious safety issue with the truck, especially since they knew this was an issue in thousands of their trucks where it was not my fault my vehicles VIN was not included as a potential recall issue, but I am following their suggestion

Engine light came on while driving and a message on dashboard said Service Transmission Now.Unable To Shift Soon. Took to dealer and they said it was the park position switch 1circuit high. Had to order part but not knowing how long to get it. Truck only has 12468 miles. Luckily I got it to the dealer ASAP. IF I were on the highway or a remote road, I feel that a serious accident would have happened. Having an electronic controlled console shifter not being able to get the truck to shift gears to slow down or stop is a real safety issue. Extended warranty does not cover anything like this. Please look into this. Thank you

Driving down the interstate at 70 miles per hour, started losing power, engine light came on. Engine started making a loud banging noise as I pulled onto an exit.

I am submitting this complaint regarding the engine timing chain failure in my 2015 GMC Terrain because I believe it presents a serious safety hazard. Before the failure, the vehicle began experiencing intermittent symptoms, including engine jerking, shaking, rough operation, abnormal engine noises, and an intermittent check engine light. While driving on the highway, the engine timing chain failed, causing the vehicle to suddenly lose power. I was traveling at highway speed and had to safely maneuver the vehicle out of traffic. The unexpected loss of power placed me and other motorists at risk of a collision because I could no longer safely maintain the flow of traffic. The vehicle was towed to an independent repair facility, where the engine was diagnosed with a timing chain failure. I was informed that the engine had sustained significant damage and required replacement. After purchasing and installing a replacement engine, that engine also began exhibiting timing chain-related symptoms immediately after installation, including abnormal rattling noises and unstable engine operation, resulting in additional repairs and the vehicle remaining unsafe to drive. I am concerned that timing chain failures in this model can occur without sufficient warning and can cause a sudden loss of engine power while the vehicle is being driven. A sudden engine failure at highway speeds creates a significant risk of a crash, injury, or death. I am requesting that this issue be investigated to determine whether it represents a safety-related defect affecting other 2015 GMC Terrain vehicles.

My 2023 GMC Yukon has had a strong mildew/musty odor coming from the HVAC system since the vehicle was new. The odor is most noticeable every time the vehicle is started after it has been sitting for several hours or overnight. After the system runs for a short time, the odor dissipates. This concern has been reported to my GMC dealer on multiple occasions. Previous repair attempts have not permanently corrected the problem, and the odor continues to worsen. The smell is now strong enough that it is embarrassing to have passengers in the vehicle. I have followed the recommended preventive measures, including replacing the cabin air filter, turning the A/C compressor off several minutes before shutting the vehicle off, and attempting to clean the HVAC system with commercially available products. None of these measures have resolved the issue. Based on discussions with other GMC Yukon owners, this appears to be a common and recurring problem affecting numerous vehicles of similar model years. Many owners report the same symptoms and repeated unsuccessful repair attempts. This suggests the issue may be related to the design or operation of the HVAC system, particularly moisture remaining on the evaporator core, rather than normal maintenance. I am requesting that GMC investigate this recurring defect and provide a permanent repair rather than temporary odor treatments. Owners should not have to repeatedly clean or service the HVAC system to address a condition that has existed since the vehicle was new.