GMC Complaints

On July 25, 2026 when starting my vehicle, it began to shake violently and I receive numerous errors, including a check engine light and displays in the infotainment, indicating there were engine and transmission errors with the vehicle. I received a text message notification and in app notification from GMC indicating that there was a critical error and provided error code P0352. This appears to be an error related to a faulty engine, this is the 6.2L V8, which is known to be problematic by GMC. Had this happened while I was driving on the interstate three minutes later, it could’ve resulted in great bodily harm or death to both myself and the general public around me. GMC was later able to reproduce the issue at the dealer, confirming the faulty equipment on the vehicle with less than 16,000 miles on it. The component was replaced by the dealer, however, the vehicle is available for inspection.

I bought a new GMC Sierra 1500 Denali with the 6.2L V8 engine in December of 2025. 7 months later, I was driving home from work. When the car started, it sounded a little louder, but not out of the ordinary. I started driving and got a strange rattle when I was getting on the highway at around 65MPH. I pulled off at the next exit and checked my fluids, checked under the car to see if anything was caught that was causing the rattle. All pressures and fluids were normal. I had Onstar run a system diagnostic. The diagnostic read normal. I got back on the highway and drove about 20 miles at 75mph. The rattling continued. 20 miles later, the check engine light came on. I had onstar run a diagnostic and came back stating “engine and transmission system problem” with two error codes. One code said “An issue has been detected in the Variable Valve Timing System adjust the timing of fuel delivery for more efficient engine operation”. The other code said “An issue has been detected in the Ignition System which oversees the timing and spark necessary to ignite fuel in your engine” Both error codes said to fix within one day. The GMC dealership was on the way home so I was going to stop there and see what they could do. I never made it to the dealer. About 2 minutes after the diagnostic, while doing 75mph on the highway, I hit the accelerator and the car did not speed up. The engine then shut off while I was in the left lane doing 75 mph. The electronics stayed on and the dash stated “press start to start engine.” I pulled over to the side of the highway and put the car in park and attempted to restart the engine. The engine never turned over again. I could not get the engine to start. I could not shift the car to neutral to have it rolled up on to the tow truck. My truck was towed to the GMC dealership and they are now replacing the engine under warranty. Will upload any maintenance paperwork once engine is replaced.

My yukon denali ultimate had only 3,788 miles on it and on 7/27 while merging onto a highway my vehicle made a sound like it was trying to shift into gear but couldn't and then while I'm pressing the accelerator pedal it's slowing down. There were tractor trailer and vehicles speeding up behind me but I couldn't speed up and I was able to pull over on the shoulder luckily and I'm thankful it did not cause an accident. My yukon would not start no matter what I tried and I ended calling a tow truck and had it towed to my local GMC delearship where I was informed that the engine had seized and they would order a new replacement engine. My yukon is still sitting at the dealership waiting for the repair.

9 months into ownership, with 24,000 miles I had complete engine failure pulling into an intersection. Slamming into park while moving and shutting down. This is a known issue with the GM 6.2 liter engines but I specifically waited to order a 2026 as this was far outside the recall window GM had in place for this known issue and was led to believe the issue was fixed going forward. The car was towed to a GM dealer and sat for 39 days for a complete engine replacement. Now, a week after it has been returned it has sputtered and shut off as I am coming to a stop requiring a restart, not unlike stalling a manual transmission car. I think your agency needs to expand the investigation far further to include 2026 models. This is a 90,000 dollar brand new family hauler that I am supposed to trust my wife and kids are safe in. Now I cannot even trust it will safely take her through an intersection. Thank you for your time.

The engine was producing a strange noise while driving and subsequently shut off. The vehicle was towed to a GMC dealership where an inspection/testing was performed. Ultimately, I was told the entire engine needed to be replaced.

On Saturday, August 15th we were driving on the freeway when with no warning the check engine light came on and the vehicle began to run poorly, and then the vehicle lost electrical power and it became difficult to steer and the brake pedal became stiff, making it difficult to stop and pull over. The vehicle would not start on command but kept running very poorly, it also became impossible to shut the vehicle off until it seized. It was later towed to a local repair shop, and today, Friday August 21st the shop confirmed that the vacuum pump on the brake assist failed and it would need a total engine replacement.

Several months ago while having my truck serviced, I asked the repair shop to inspect the ball joints on the passenger side because they would make a popping noise when turning the wheel. The shop inspected them and said that was a normal sound due tot he factory lift. Recently I was driving home and about to turn into my lane when the front passenger wheel assembly collapsed under the truck due to the a upper ball joint failure separating the brake line and loss of steering. At the time, I was only going about 25mph and the truck slid to a stop on its own. The truck has 65,000 miles on it and if this had happen at highway speeds personal injury to myself and others would have been likely. The repair cost were $7,500. Fortunately I purchased an extended warranty which covered all but $1,700 of the repair.

The contact owns a 2018 GMC Terrain. The contact stated that while her son was driving 45 MPH, the brake pedal was firm while depressed. There was no warning light illuminated. Due to the failure, excessive force was needed on the brake pedal to stop the vehicle. The contact was able to drive the vehicle to the residence. The following day, the vehicle was taken to an independent mechanic. The mechanic diagnosed the vehicle with an inoperable vacuum pump that was shredded and needed to be replaced. The manufacturer was notified of the failure and informed the contact that the VIN was not under recall. The contact was then referred to the NHTSA Hotline for assistance. The vehicle was not yet repaired. The failure mileage was approximately 117,000.

Driving on busy road when heard a squealing from the engine bay of the vehicle. Moments later the vehicle lost power. It was a very dangerous situation traveling approximately 45mph on a multi-lane road in urban St. Louis Missouri. There was not a check engine light prior. The vehicle had a recall performed per GMC instructions prior (this amounted to a different viscosity oil....). The breakdown stranded my family and I while on vacation in another city. The vehicle was towed to a local GMC dealership and was diagnosed as a seized engine related to the recall. The engine is scheduled to be replaced as no cost through GMC's extended service. They have not provided coverage for the towing, for the multiple ride shares needed to get around on vacation, for the rental car needed to get home, or a rental car to help us with day-to-day life during the estimated 6-8 weeks we will be waiting. My family was at risk, other motorists on the parkway were at risk. It was pure luck and quick thinking that saved injury or loss of life. It is completely unbelievable GMC is letting these vehicles be on the road for peoples safety and for the money people pay as a consumer.

The contact owns a 2023 GMC Yukon. The contact stated that while driving at an undisclosed speed, the vehicle made an abnormal clunking sound. The contact pulled over and inspected under the hood. The vehicle was restarted, and the engine revved six times with smoke coming from under the hood. The contact stated that the transmission was previously replaced. The vehicle was towed to the dealer, who discovered that Jiffy Lube had used an incorrect engine oil during an oil change. The contact was informed to contact Jiffy Lube and file a claim. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 36,000.