2021 GMC Sierra 1500 Complaints

ENGINE AND ENGINE COOLING — Filed 06/16/2026

The contact owns a 2021 GMC Sierra 1500. The contact stated that while driving 35 MPH, the engine was making an abnormal sound, and the vehicle failed to accelerate. The engine was popping and making cranking sounds, with several unknown warning lights illuminated. The vehicle was driven back to the residence with the issues. The contact referenced NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling); as a possible cause for the failure; however, the VIN was not included in the recall. The vehicle was taken to a dealer where it was determined that there was metal fragments found in the oil filter, and recommended that the engine be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 50,000.

ENGINE — Filed 07/11/2026

I'm not sure if they've pulled it out yet. They said two weeks to get motor. Engine started shaking and then started knocking. Had wrecker take it to GMC dealer they said it needs an engine. It is a 2021 6.2 carbon pro 1500 Sierra AT4 it did not come up on recall list and I don't know why? it obviously the same problem.

ENGINE — Filed 07/11/2026

At 115,000 the coolant control valve has gone out. GM acknowledges this issues in 2020 model trucks. My truck is a 21 and displaying the same characteristics. A simple google search will show this is a known issue in 2021 vehicles as well. In 2020 model trucks GM has provided a special 150,000 mile warranty to replace this part. GM needs to step up and provide a proper warranty/recall for the affected 2021 models.

FUEL/PROPULSION SYSTEM — Filed 07/16/2026

P1098 code indicating stuck/ unresponsive engine coolant control valve. N252508341 exists for this part; however claim is my VIN is not covered under the bulletin or included on any standard warranty coverage. Part should last more than 150k miles, vehicle less than 90k. Less than 2 weeks ago suffered a complete EBPV failure that destroyed coolant and DEF lines, also not covered. No explanation for why my specific VIN (a 3.0L diesel in the supposedly covered MY) is excluded. Have been unable to find evidence of any applicable vehicles that were 'covered' under this bulletin. Fault forces an unexpected derate which can engage while accelerating, including while merging into freeway traffic. This is an obvious safety hazard. Engine check light illuminates approximately 30 to 60 seconds before derate limits top speed and throttle response. No messages to operator. Dealer has confirmed issue.

POWER TRAIN — Filed 06/01/2026

The 10 speed automatic transmission shakes and jumps between gears. The transmission also shakes and rumbles at cruising speeds. The diesel engine version of this truck is already recalled. My truck is a gas engine and should also be recalled. This is the same defective 10 speed transmission used in all GM vehicles and recalled in many. This vehicle needs to be recalled and fix before the wheels lock up and kill someone.

ENGINE — Filed 07/09/2026

I was driving and my check engine light came on a mile from my house. I drove home and the next morning, I started my truck. It was loud and pulsating like it wanted to stall out. I had it towed to a repair shop. They plugged into the truck and said it was giving code P0016. I had it towed to another place and that it is where it is sitting now. I also received a email from onstar saying "A critical issue with the engine and transmission system in your 2021 GMC sierra Crew Cab has been detected. P0016 was detected. I searched my VIN # and it says that there are no recalls on my truck. I do see that there was a silent recall on the engine that is in my truck.

ELECTRICAL SYSTEM,ENGINE,FUEL/PROPULSION SYSTEM — Filed 06/02/2026

I am submitting supplemental evidence regarding my 2021 GMC Sierra (VIN [XXX]) for Recall Query RQ26001, Campaign 25V-274. Despite multiple repair attempts, my vehicle remains unsafe and non-compliant with GM Service Bulletin N252494002. The recall remedy was performed deficiently. [XXX] Northeast Buick GMC installed a remanufactured short block instead of the required complete engine, reused the original seized-engine oil pan (which continues to leak), and failed to address critical electrical damage. Documentation proves they deleted Labor Operation 14BUZ (Engine Electrical) after their technician noted a blown mega fuse. A second dealer, Penske Chevrolet, subsequently deleted Labor Operation 77CVZ01 from my repair order, demonstrating a systemic pattern of ignoring recall-required repairs. Electrical damage has cascaded, resulting in a burnt fuse block and active faults P0615, P0617, P26E4, P26E6, U0623, and U0284. More critically, within 24 miles of my last service, the vehicle developed a new, severe safety failure: the "Service Brake Pad Monitor" system failed, accompanied by a red "Service System" dashboard alert and a noticeably spongy brake pedal. These brakes were recently serviced, yet this failure introduces a new risk of crash not present prior to the recall "remedy." GM Executive Resolution Case XXX has provided no resolution, reimbursement, or safety assurance, ignoring all deadlines since XXX. I possess extensive documentation, including service orders showing deleted labor operations and diagnostic logs. I request this update be integrated into the investigation of RQ26001, as the current remedy is demonstrably ineffective and has exacerbated safety hazards. The manufacturer’s refusal to remediate these issues, despite my compliance, leaves me with an unsafe vehicle and significant financial loss. I am prepared to provide all supporting records to substantiate this complaint. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

POWER TRAIN — Filed 12/31/1969

transmission shuddering, harsh or delayed shifting, and erratic gear changes. The truck jerks really bad during each shift of the ten speeds. A vibration or shudder typically occurring at speeds between 25-65 mph under light throttle. Also makes a bad noise every times it’s shifting. I have no lights on the dash and the gmc app tells me everything is fine when clearly it’s not . I see there’s a recall for my year and make but for some reason my vin doesn’t fall in the category

POWER TRAIN — Filed 06/04/2026

My car suffered a catastrophic engine failure, metal schards were found in the oil filter and was left out of the 2021 recall 25V274. The in service date of vehicle is March 13, 2021. The car was 83 days out of warranty when the engine failed. The truck has 47,000 miles on it. They are now trying to charge us, barter with us. They have gone from $2800 for repair, negotiated down to $100 to sign this off as a good will repair stripping us of lemon law rights and future recall remedies. Car is currently sitting at the dealership.

ENGINE — Filed 07/01/2026

The contact owns a 2021 GMC Sierra 1500. The contact stated that while turning the ignition on, the "Service Parking Brake" message was displayed, and the check engine warning light illuminated. Additionally, the engine ran rough. The vehicle was taken to the dealer, where it was diagnosed that the engine lifters needed to be replaced; however, the dealer could not diagnose if there was further engine damage until the lifter repair was completed. The manufacturer was made aware of the failure. The failure mileage was approximately 72,530.