GMC Complaints

I OWN A 2018 GMC SIERRA DENALI ULTIMATE, The truck has the 6.2 engine which had the lifter issue as stated with the current situation. At the time, the truck had 37,000 miles when the issues started. I purchased the truck from Andy Mohr with 8806 miles on it in November of 2019. I worked overseas for the DOD so that’s why the miles are low. After I got it fixed, ($4500 dollars at Hare Chevrolet) I experienced the transmission shake while driving home from work with my children in it. The transmission was shaking so bad the whole cab was rocking.That repair was $3,300. Now, the truck has piston slap and rod issues and currently at Hare Chevrolet for service. I was told I need a full rebuild ($12,000 dollars or a new engine $14000 dollars). As a retired Air Force veteran, I didn’t expect issues like this, especially when I baby the truck and it currently has 40,530 miles. I had regular oil changes and service, yet now stuck with a high class truck that has serious issues that seem to be ignored by GM and Andy Mohr GMC. Andy Mohr sold me an extended warranty at time of purchase but I paid for a year and a half that wasn’t usable. If I had that warranty I would be covered now.But besides that, it’s a Denali, I shouldn’t be having a new engine at 40,530 miles. I am happy that there is an investigation but it needs to be widened because my truck was right before the new model rollout but I am having the same issues. If needed, I have all my receipts and information and will provide the service rep at Hare. The reason why its at Hare vs Andy Mohr is due to me catching them not fully servicing my truck and joy riding my Camaro ZL1 after an oil change before I went home for a funeral.

When driving at about 30 mph the truck randomly shut off and would not start or try to start. I was later told the engine crankshaft rod bearings seized.

While accelerating on the highway the truck started to vibrate along with a loud tick, CEL came on for misfire and traction control, hard shifting to where I could park at a safe area to wait for a tow. Kids in the car with me 90 plus degree day on the side of the highway.

Truck started to vibrate and loud tick sound, CEL for misfire and traction control. Hard shifting until I could pull to a safe area to call for a tow. Around 76k miles on the truck when it happened.

The engine has a knocking sound. I took it into the dealer and they replaced the exhaust system thinking that was the problem. However, the knocking still happens intermittently. I have video documentation of the noise.

1-At approximately 40,000 miles, my transmission was replaced under warranty. It had been failing since approximately 2000 miles having a very hard time shifting between first and second gear. It was finally replaced at 40,000 miles. 2- At approximately 45,000 miles I took my truck into the dealership for this latest recall on the 6.2 L failure for inspection. Vehicle is inspected and I was told I would need to have an engine replacement. I was told that there was no ETA on when a replacement engine would be available and that I would be contacted when one was. Afterwards I was sent back home in the truck they just inspected for potential engine failure and said had a bad engine. As of now, I’m still waiting on a word of a new engine and my truck is still operating, but leaves me concerned that it could fail at any moment while driving it.

For the second time since I have owned the vehicle that was purchased brand new. The engine seized during driving on the highway and began making loud noises that was knocking and jerking the vehicle. The issue occurred initially around 15,000 miles and was diagnosed as lifter failure, was repaired and returned in July 2022. At 64,000 miles on January 15, 2026, while on an interstate the engine did the same thing and the vehicle went into limp mode. It has been diagnosed as lifter failure this second time and is awaiting appropriate repairs. Both incidents put myself in passengers at danger due to the nature in which the vehicle entered limp mode on the highway.

I have a 2023 GMC Delnali 1500 and the engine blew up 1-14-26 after the local CMC dealer 2 months ago done a check up recall from GMC that said they would do a test on the engine and cahnge the oil with a heavier weight oil that would solve the problem. After the dealer done the test and changed the oil to a heavier weight I was told all was good. Well 2 months later the engine blew up while I was driving down the road at 50 miles and the truck lost all propulsion. I had the truck towed to my house because noone knew what was wrong with it. I called the local dealer the next day and I had the truck towed to them. They checked the engine and said it blew apart and that GMC will replace the engine and also install a new radiator when all the parts are available. The dealership Laura Buick GMC and employees has been fantastic and have supplied me with a vehicle to drive till the repair is finished.

Original inspection and recall was performed on my 6.2 engine on 12/02/25 and the engine failed on 1/15/26 , the vehicle is in the shop awaiting new Engine

Warning about reduced acceleration and need for immediate servicing. Dealership reports notice about this issue by using diagnostic codes. Needs engine and turbo charger replaced. Vehicle has only 6500 miles on it.