GMC Complaints

With 94 Miles my brand new GMC Canyon AT4 I leased had a catastrophic failure while i was driving it, the front axle essentially exploded. The findings were that their was no oil/lubricant installed in it from the factory which made this happen. I now have to wait many months for the dealership to repair my vehicle while i have a "loaner" with a bunch of restrictions on it. And i have to pay my lease the entire time it is being worked on because of a factory fault. If i had been going more than 25 mph this would have resulted in a crash/injury.

2020 GMC Sierra 1500 began experiencing a slight knocking sound - mechanic diagnosed as a crankshaft issue. As of last night, 5/10, the truck's knocking sound got extremely loud, the exhaust pipe emitted smoke, and the truck began "bucking." No warning messages or lamps appeared.

First incident April 9 2024 not even a month after purchased. Vehicle dashboard lit up light a Christmas tree all warning lights while driving on highway. Vehicle shook and sputtered and turned off. The vehicle was serviced explanation given was loose spark plugs on a new vehicle. 2nd incident roughly month after recall repair for engine propulsion campaign. February 26 and 27 2026 . While driving the following lights came on Engine failure ,Brake failure , Service Transmission now unable to shift soon. I was terrified because I could not control the vehicle. I had the vehicle towed to the dealership. The answer to the issues was Battery failure. Third incident April 17th 2026 I driving on highway 70 miles check engine light comes on flashes dashboard goes dark. Vechicle sputters and shut down. I restarted the vehicle the warning on the display disappeared and the vehicle restarted. I reached returned the vehicle again to the dealership because the problem resumed slowing down even though I’m depressing the gas. Vehicle is shifting and dragging. Resulting unexpected lurching. My vehicle has been at the dealership since end of April 2026 it remains there currently. My representative stated a code indicating misfiring has appeared 18 times. Also everyday my vehicle keeps saying software update even I installed the update and it says complete. I know GM is not updating my vehicle software everyday. That indicates there is a computer issue as well. My anxiety level is through the roof at this point. I complained before about this same failures in a Cadillac Escalade prior to it lurching forward and crashing. I filed a complaint before February 2024 . There is something really wrong with GM engines and software. I know I’m not the only one experiencing these problems

A common issue in GMC vehicles (particularly 2017–2020 Acadias) is a "Steering Assist Reduced" warning message triggered by a failed engine coolant thermostat that gets stuck open. This causes the engine to run too cold (P0128 code), causing the computer to reduce steering assist (which is dangerous) and run fans on high, also the air conditioner fails. I have seen many complaints about this and it seems to be a manufacturers problem. GMC put out a repair bulletin for the 2021 models with this issue. It's time to address these other years.

I am filing this formal complaint to report a series of catastrophic, life-threatening mechanical failures involving my 2023 GMC Yukon. This vehicle has become a weapon on the road, exhibiting erratic behaviors that nearly resulted in a multi-vehicle fatality on a high-speed highway.1. High-Speed Power Loss (Highway Failure while my wife was traveling at 60 MPH in heavy highway traffic, the vehicle’s transmission spontaneously and without warning disengaged and shifted into Neutral. This caused an immediate and total loss of motive power. In a split second, my wife was left piloting a 6,000-pound unpowered projectile in the middle of high-speed traffic. By the grace of God alone, she managed to navigate to the shoulder without being rear-ended. This is a clear "Sudden Loss of Motive Power" defect that poses an immediate threat to life. 2. Unintended Directional Movement (Reverse Shift) Following a total engine replacement—a repair that took over 45 days—the vehicle has now developed a new, terrifying defect. While stopped at a traffic light, the vehicle spontaneously engaged in Reverse. This unintended movement occurred without driver input, creating a high risk of pedestrian strikes and intersection collisions. 3. Systematic Failure and Dealer Evasion The vehicle previously exhibited "ghost shifts" into Park and Neutral at low speeds. Despite my repeated warnings to the General Motors service department, I was dismissed until the engine ultimately failed. Furthermore, the dealership has been inconsistent and evasive regarding the serial numbers of the replacement components, leading me to believe that unsafe or defective parts are being recycled into these vehicles. General Motors is aware of these powertrain defects, yet they continue to allow these "death traps" to remain on the road. My family will not be the "crash test dummies" for GM’s manufacturing negligence

Coolant temperature sensor failed - it is still in the engine. the fan stays on high all the time. And the AC does not want to turn on. The car is extremely hot to drive in during the summer months. I have to transport persons who are seniors and in their mid 80s. It is not safe to drive this car in the summer. I can't tell if its over heating or what is happening. The coolant temperature gauge does not work. The dealer said my car is out of warranty and that the AC will not start until the sensor is replaced. I said that it has less than 50,000 miles. They will not help me. The vehicle has not been inspected anyone other than the service mechanic. The engine light start coming on about a month ago. I drove first to an autoparts store to see if they could help. this is the first time I learned that it could be a bad sensor.

The curtain airbags on both the passenger and driver side deployed while driving down the road. The truck is available for inspection although the deployed bags have been cut off in order to drive it home. Pictures were taken before doing so and are available for inspection. My son is pretty shaken up and has injuries to his shoulder, face and his ears are ringing.

The relay for the fan at the top of the fuse/relay box on the right side when facing the front of the vehicle. (under the hood) Gets hot and blows the relay and melts the spot where the relay prongs plug in. Causing the need for a new fuse box and circuit problems within the fuse box connectors. The fans, specifically the a/c fan does not kick on when turning on the a/c and the low speed fan does not kick on at all until the secondary temp fan kicks on after the temperature raises past the normal operating range. Which an overheating engine is bad for all parts of the engine which can and sooner or later will lead to a catastrophic failure putting the operator and other motorists life's at risk.This time it created a small fire that was extinguished only because the fuse box cover was off and I was looking at it as it happened, putting the cover back on extinguished the fire. This is the third time it has happened with the exact same problem. You tube is full of videos with the exact same problem.

GM Duramax L5P diesel engine electrical connector for #4 fuel injector. This failure caused the Diesel exhaust brake, which controls downhill speed, to disengage, extreme shaking of the vehicle, emissions system warning and speed limiting. This occurred while descending a steep grade while towing a 34 feet long, 10,000 pound trailer. This is a known issue with this diesel engine and documented in GM Technical Service Bulletin 23-NA-027. Inspection and repair at a GM dealership confirmed a known issue with the #4 injector pigtail connector caused by improper wire routing and interference wit the Sound Shield and Valve Cover Heat Shield This was a sudden failure of the #4 pigtail connector with no advance warning. In addition to violent shaking of the vehicle, multiple warnings on the DIC indicating that the Diesel Brake was disengaged, the emission system had an issue, and speed would be limited.

The engine started having knocking and I took it to the dealership and now I have been waiting 45 days with no engine replacement in site after they told me the engine failed completely. It had 3,900 miles on the engine!