GMC Complaints

This malfunction is ongoing and the dealership cannot fix the problem. The first time it happened in September 2025. I was driving down the road and the gauges started to go crazy. The screen on the dash said reduced acceleration. Then it said Service ESC. Then it said Service Traction Control. It would not let me go over 40 mph. I took it to the dealership and they told me I needed a valve body replacement. They installed the valve body and that did not fix the problem. It happened again and said reduced acceleration took over forcing me to pull over on the side of the road. The GMC dealership said to bring it in again but they could not reproduce the malfunction after driving for a week. It happens randomly. The third time this happened I was traveling up interstate 24 at about 70 mph. There were semi trucks around me when the malfunction happened and my acceleration and speed was reduced throwing the RPMs as high as they would go, and I was almost hit by a semi trying to move out of the way and onto the shoulder of the interstate I tried to accelerate to get out of the way of the semi truck but could not. I had to swerve over almost losing control of my truck. I informed the dealership that this had happened again and they asked me to bring it in. I did. They told me they were going to clean corrosion off of ground wires, and that should fix the problem. It did not. This keeps happening and I feel that the vehicle is not safe to drive. I do not know when it will happen again. I travel for a living and I feel the vehicle is unsafe to operate.

The oil consumption is abnormal and burns almost 2.5 to 3 quarts between oil changes. This can be a heavy risk to the engine if I don’t check on it every couple weeks. I don’t think after the price I’ve paid for this truck that I should have this concern and this should not be the case

My vehicle has lurched forward upon the first engine start of the day, under no throttle, on several occasions, throughout the life of my vehicle. Shortly after starting my 6.2 engine in my garage, if I shift my 8L90 transmission into Drive as soon as the engine RPMs settle to idle, the vehicle will lurch forward, screeching the tires. Luckily, I had my foot on the brake hard enough such that no one was injured. The harsh transmission shift into drive is dangerous, possible injuring passengers or my garage door. I've learned that if I wait 5 to 10 seconds, allowing the engine to idle (while the transmission oil becomes pressurized ??), then the shift into drive is normal, without any lurch.

After 38,000 miles and 8 years of normal service (mix of city, highway, and 10% towing), my 8L90 transmission began to shudder occasionally. The problem first became apparent when driving slightly uphill, on cruise control at about 50 mph, or while slightly accelerating on a flat road, with no load in the box, and no trailer. It felt like I was driving across a rough patch of asphalt or rumble strips. Every half mile or so, it would shudder. Slowing down or speeding up stopped the rumble. The problem proved not to be caused by tires, U-joints, or AFM. The problem in fact was caused by defective GM transmission fluid, which was sold as "sealed for life", and rated for 200,000 miles, as factory-installed. That proved to be BS. If not repaired, this problem would lead to transmission lockup and/or lack of propulsion, which could contribute to a vehicle crash. The problem was solved by installing AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid, Product Code: ATLTP-CA. If GM properly cared for their customers, to make up for false advertising at the time of purchase, GM should publish and pay for GM Service Bulletin #20-NA-142, for all 8L90 owners, instructing owners to replace their transmission fluid every 5 years or 40,000 miles, whichever comes first.

I purchased a Yukon Denali 6.2L in March of 2022 brand new from Bob Johnsons in Rochester NY. On [XXX] at 12,577 miles the engine went through a catastrophic failure, while driving, the vehicle began to make very loud noises. The vehicle was taken to Bob Johnsons GMC 4389 West Ridge Road Rochester, NY 14626. The repair notes #3 main bearing thrust portion had come apart. The vehicle was out of service from 4/3/2023 to 4/19/2023 for engine replacement. On [XXX] at 50,244 miles on the vehicle, I was driving down a busy highway during holiday traffic and the vehicle went into neutral and would not start, we immediately turned the flashing lights on, unrolled the windows and began to show distress to ensure we were not hit by passing cars. We made it to safety and called Onstar for assistance, on this occurrence due to the vehicle not starting we were unable to get the vehicle back in to the neutral position to be able to roll the vehicle. The vehicle was towed to Bob Johnsons GMC due to the Thanksgiving holiday, the vehicle was brought in 11/28/2025, and deemed to need another engine replacement. On November 28th I called to file a claim with General Motors and was called back by Stephanie on November 29th and was told they would get back to me if they had any options as now this is the 3rd engine replacement. On December 3rd, a new woman called also named Stephanie and advised me they were still undergoing options, as I requested a Buy Back with Trade Assistance. On December 9th, my final call from General Motors advisor Stephanie, I was told I do not qualify for a buy back because I placed too many miles on the vehicle between engine failures. The vehicle was out of service from 11/26/26-12/29/26 for engine replacement. On [XXX] 2 weeks and 4 days after the vehicle going back into service, the engine failed again, only driving approximately 245 miles. I am currently waiting on the 4th engine replacement with no updates. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6

I habe a 2021 Yukon Denali and i have had engine failure on the road. Lifter issues and rod issues. i have paid out of pocket to fix it because my truck wasnt part of the recall. But i had the first failure in November 2024. Second failure January 2026.

4 months after bring my truck back to the dealership for a body valve issue on the 10 speed transmission. The truck went into limp mode while I was driving.

Vehicle 4WD performs poorly with car fishtailing at very low speeds 30 MPH in a straight lane. Very scary . Feels unsafe to drive . Brand new tires were installed prior to that. So not a tire issue.

My TAILGATE kept opening randomly and ENGINE WAS MAKING CLUNKING SOUND initially. Lost many tools on the highway once when it opened. Dealership told me my truck is not covered under a recall for both issues, even though other similar vehicles are. I refused to pay anything to have it fixed. They claimed my truck “wasn’t built in the factory that has recalls”. A month later the STARTER AND BATTERY burned up when I started up the truck, something locked up it sounded like. Eventually it started but didn’t sound right. A few days later the engine finally blew up. I paid out of pocket for everything for that trip. It’s currently back at the dealer being repaired with a new engine for the recall but GMC refuses to pay for the initial clunking/starter/battery and the tailgate issues. I’ve encored so many charges with tows and rentals from all these issues. I would like full reimbursement for everything.

Driving at approximately 30-35MPH merging in traffic, the transmission shuttered and went into reduced power mode. ECM reported a 747 code and valve body failure.