2021 GMC SIERRA 1500 Complaints

I've now had 2 engines fail catastrophically, One at 19,191 miles and the second failure at 80,661. Both are the 6.2L engine. The first had crank bearings that were black. The second I was not informed of the cause but that it was seized leaving me stranded on the roadside.

Engine failed and had to be replaced. GMC was absolutely no help had to bring to local gas station where i had to pay almost $12,000 to get it fixed. The truck has been in shop frequently for oil issues with this motor but GMC just jerks you around. I am in sales and need my vehicle to support my family

While driving the vehicle shut off in the middle of the roadway. It sat in the road till it got towed. Brought it to the dealership where it was purchased and they said the engine was blown. Themis vehicle is equipped with the 6.2 motor. It happened February 16th. The dealership confirmed the engine failed. It is siting currently at the dealership and could be available for inspection.

AFM lifters failed which caused cam shaft to collapse under 35k miles. Had to remove while front end to repair

Subject: Complaint Regarding Recurring Engine Failure in 2021 GMC Sierra AT4 Dear National Highway Traffic Safety Administration, I am writing to formally express my concern regarding recurring engine failures in my 2021 GMC Sierra AT4 (6.2L engine). At 23,000 miles, the vehicle suffered a complete breakdown due to failure of cylinder #8, lifters, and push rods. General Motors covered the repairs at that time. However, at 97,000 miles, the exact same issue reoccurred, resulting in significant engine damage. The dealership diagnosed a misfire in cylinder #8, leading to the removal of the right cylinder head, where they found a bent push rod, spun lifter, damaged camshaft lobe, and lifter roller. The repair estimate totals $9,746, but GM has refused to cover the costs, despite us having an extended warranty purchased from the dealership. This recurring failure raises serious concerns about engine reliability and manufacturing defects in General Motors vehicles. I urge the NHTSA to investigate this issue, as multiple GMC and Chevrolet owners have reported similar problems with the 6.2L engine lifter and camshaft system. This is not just a costly repair but a potential safety hazard that GM has failed to properly address. Thank you for your attention to this matter. I appreciate any guidance or action the NHTSA can take to hold GM accountable and ensure consumer protection.

The contact owns a 2021 GMC Sierra 1500. The contact stated that the tailgate opened unintendedly while driving, and while the vehicle was parked. The contact stated that the failure had been recurring. The vehicle was taken to the dealer but was not diagnosed or repaired. The contact related the failure to GM Campaign Number: N232426400. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline to report the failure. The failure mileage was approximately 76,000.

My Vehicle went into the dealer on January 21, 2025. My initial complaint was tapping noise, I was advised that my vehicle had collapse lifters issue several days later I was informed that they have found metal shards in the lower end and found a bad crank bearing and crank. I was told that the vehicle will need an engine replacement, and that the engine is on back order with no date of fulfilment. My vehicle has 66,700 miles I was advised was out of warranty and that GM will only cover half of the estimated cost of 11,000.00.

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving at approximately 80 MPH, the vehicle stalled and failed to return to normal operation. No warning light was illuminated. The vehicle was towed to be diagnosed. The contact was informed that the rod bearings needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 134,000.

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving at an undisclosed speed, the transmission slammed into gear and the rear wheels locked up. In addition, the vehicle decelerated independently. The vehicle was driven to the shoulder of the road and turned off. The vehicle was restarted, and the contact noticed that the vehicle was independently reset. The vehicle was taken to the dealer where it was diagnosed with a failed wiring harness. The contact was informed that the wiring harness needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure and a case was filed. The contact was advised to contact the NHTSA Hotline and report the failure. The failure mileage was approximately 60,129.

The contact owns a 2021 GMC Sierra 1500. The contact stated while driving 55 MPH, the vehicle started making a knocking sound. There were no warning lights illuminated. The contact picked up his son from school and drove the vehicle to the dealer. The contact stated that while depressing the accelerator pedal, the knocking sound became louder, and the vehicle was losing motive power. The vehicle was taken to a dealer and diagnosed with engine failure. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 58,522.