GMC Complaints

received my truck back after replacement of the front transmission pump and idle gear, the same day the transmission had horrible down shifts, sometimes it would just downshift into neutral and bounce off the rev limiter. the service advisor told me that my transmission had to "relearn" my driving habits when I called him and would take 200-400 miles.. i drove it one more day and drove it back to the dealer to have them drive it. the agreed that something was wrong, but didn't know what and had to contact gm engineers. 2 days later they told me that the valve body needs to be replaced. I dropped it off to find out that it had been ordered with zero ETA of when they will receive it.. so now im stuck with a loaner and no ETA on when parts will be available.

I am reporting a serious mechanical and safety issue with my 2019 GMC Sierra 1500 (5.3L engine). The truck began misfiring, running rough, and would frequently “jump” and shut off while driving — creating an unsafe situation on the road. We attempted several repairs to resolve the issue: •Transmission flush •Replaced the intake manifold gasket •Replaced all eight fuel injectors •Inspected all ignition coils •Replaced faulty sensors The vehicle repeatedly showed a Cylinder 8 misfire, even after these repairs. Eventually, it was diagnosed that both the lifters and camshaft are bad, and the engine now needs a full replacement. This is extremely concerning because the truck has only about 47,000 miles on it. We brought it to the dealership in September 2024, while it was still under warranty, and told them it wasn’t running right. The dealership said there was nothing wrong. Now that the warranty has expired, GM is refusing to help with any repairs. This appears to be a manufacturing defect that was not properly diagnosed while under warranty. Engine failure at such low mileage, especially with early warning signs and repeated diagnostic errors, should be investigated as a serious reliability and safety concern.

Engine seized while at idle speed and has to be replaced. It was a catastrophic event, but not covered under the current recall for 6.2L L87 engines.

• The airbag system failed to deploy during a collision that resulted in the total loss of the vehicle. Additionally, the vehicle was operating with a 17” spare tire (undersized compared to the standard 20” wheels), which may have contributed to the accident. The vehicle has been totaled and is currently in the possession of the insurance company, but may be available for inspection upon request. • Despite the severity of the collision, none of the airbags deployed, which could have resulted in serious injury if the circumstances were different. The use of an undersized 17” spare tire may have affected the vehicle’s stability, braking, or performance, contributing to the crash. • No. The vehicle was declared a total loss and has not been evaluated for defect reproduction by a dealer or service center. However, I am aware of related recalls and lawsuits regarding both improper spare tire sizing and airbag non-deployment in 2020–2021 GMC Sierra models. • The vehicle has been inspected by the insurance company during the total loss evaluation. A police report was also completed at the scene of the accident. To my knowledge, the manufacturer (GM) has not inspected the vehicle at this time. • No. There were no warning lights, messages, or symptoms prior to the crash. The vehicle gave no indication of any issue with the airbags or tire compatibility leading up to the accident. I was involved in an accident in my 2021 GMC Sierra. At the time, the vehicle was operating with a 17” spare tire installed, which I later discovered may be significantly undersized compared to the standard 20” wheels. During the crash, the impact was severe enough to total the vehicle, but none of the airbags deployed. Fortunately, there were no injuries, but I believe the non-deployment of the airbags represents a critical product safety defect. I’ve since learned that GM has recalled similar vehicles for incorrect spare tires, and that lawsuits have been filed regarding calibration issues.

I was driving on the highway going about 50 mph and the engine just stopped. It was very dangerous, and I couldn't get to a completely safe spot. I was stuck for 45 minutes there until police could get to my Yukon and help provide safety. I had 2 other passengers in the car. All of us were put at great risk and the surrounding traffic was also at risk. The Triple A towing took over an hour to get the vehicle on a flatbed because they couldn't get the Yukon in Neutral. There were absolutely no warning lights or any weird noises, the car shifted out of drive and would not go back into any gear. I am waiting for the dealership to decide what to do. My main reason for writing this complaint is this is a BIG HAZARD, not only for people who drive/ride in these vehicles but for every vehicle on the roads around them. When they stop with no warning, accidents and I'm sure some with fatalities will happen. This is a critical situation, and these vehicles should all be off the road. My Yukon was in my dealership service for an oil change about 1 week prior to this incident and I had a long conversation about the recall. They said my Yukon looked great and nothing was needed unless I had any problems. Since there have been so many others with the failed engine, ALL vehicles with this recall should be off the road to prevent totally innocent people from being in these dangerous situations. This is preventable if these cars are forbidden on the roads!!! GM must take responsibility before lives are lost due to this negligent reaction of issuing a recall but saying it is safe to keep driving unless there is a problem. If the first sign of a problem is failure with resulting catastrophic outcomes, then just issuing a recall is not enough. This must be addressed, PLEASE. This was a terrifying experience for me and my riders. I have no idea if the police filed the report but they spent alot of time trying to keep everything safe due to this issue.

The contact owns a 2020 GMC Sierra 1500. The contact stated that while driving 60 MPH, the horn failed to function as intended. There were no warning lights illuminated. The contact stated that on a separate occasion, the right lane sensor stopped working as intended. There were no warning lights illuminated. The contact stated that on a separate occasion, while driving 60 MPH in the rain or on rough asphalt, the rear suspension caused the vehicle to fishtail to the right. The contact turned to the left to control the vehicle. The contact stated that the vehicle returned to normal functionality after the failure. The low transmission fluid warning light was illuminated. The vehicle was taken to an independent mechanic, who diagnosed the vehicle with an electrical systems failure. The independent mechanic informed the contact that there was adequate transmission fluid inside the transmission, and it was unclear why the warning light was illuminated. The contact was informed that weights were added to the wheels to balance each wheel. The vehicle was not yet repaired for the other failures. The contact stated that the transmission was replaced a year prior to the failure, and the horn had failed to function soon after the transmission replacement. The manufacturer was made aware of the failure. The failure mileage was approximately 68,000.

I received a recall notice for my 2024 GMC Sierra Denali Ultimate (6.2L engine), related to defective lifters that can cause engine damage. My truck was built in April 2024, and I've been told by some sources that certain 2024s may have the updated lifters, but neither my dealership nor GMC will confirm whether my truck is affected or safe. I’ve asked multiple times for VIN-specific confirmation of the engine components — no one has been able to tell me if my vehicle has the faulty parts or not. I was told to just keep using the oil they recommend or wait for a diagnostic tool GM hasn’t even released yet. That’s not enough. I’m planning to take my family, including my grandchildren, on a long road trip soon, and I don’t feel safe putting them in this truck without answers. For a vehicle that cost over $85,000, I shouldn’t be left guessing whether the engine could fail on the road. I’m filing this complaint because GM is not giving me a straight answer, and I think this is a serious safety concern.

For whatever reason our 2021 GMC Yukon Denali is not listed in the current 2025 GMC motor recall including cams and lifters and accompanying parts. While driving our truck about a mile from the house the vehicle began seizing and shaking (almost as if we had blown several tires); we immediately pulled over and accessed. Called Dealership and had truck towed there immediately. We are told that it needs cams and lifters and that b/c our VIN does not pull up a recall that the repairs will cost ~$9800.

My name is [XXX] , and I am writing to formally lodge a complaint regarding a serious safety defect in my 2023 GMC Yukon with a 3.0 Duramax diesel engine. The issue involves the transmission valve body, which has caused rear wheel lockup at highway speeds. I experienced this issue at 34,000 miles on my vehicle, and it has been in the shop for over 5 weeks with no estimated time on parts availability. Despite opening a case with GM support, as detailed in the attached email transcript, I have not received a resolution. GM has refused to replace the complete transmission on the vehicle and only offered to replace the valve body. This is unacceptable as the defective valve body has already caused damage to the transmission. I also opened a BBB Auto Line case, which was closed immediately after I denied the offer from the GM support representative. This raises concerns about a potential conflict of interest, as the BBB Auto Line seemed aware of my interactions with GM support. I am seeking a complete transmission replacement with a valve body upgrade kit from NextGen transmission, which I believe would resolve the issue. However, GM has not accepted this offer. I request that the NHTSA investigate this matter promptly to ensure the safety of my vehicle and others that may be affected by this defect. If this issue is not resolved, I will have no choice but to pursue legal action. Thank you for your prompt attention to this matter. Sincerely, [XXX] [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I was driving and without warning the engine stopped. Luckily I was on a neighborhood street and was just left in the middle of the road without incident. However, if I was turning on a left into traffic or on a major highway I would hate to think what would of happened. Again, this motor gave zero indication it was going to fail. It did not knock etc. Truck is currently at the dealer waiting for a new engine. This recall will lead to fatalities if others fail in this manner.