I am writing to formally request that General Motors repurchase my 2026 GMC Sierra 1500, currently with approximately 9,445 miles, due to a serious and unresolved mechanical defect that poses a significant safety risk. Since purchasing this vehicle, I have experienced four separate incidents involving a complete and unexpected loss of engine power, causing the truck to become inoperable. In each instance, the vehicle suddenly lost propulsion and came to a stop without warning. While three of these events occurred while operating the vehicle near my residence, one incident occurred while I was attempting to merge onto a highway. Fortunately, traffic conditions at the time prevented a collision or serious injury. However, the sudden loss of power while entering a highway created an extremely dangerous situation and exposed both myself and other motorists to substantial risk. The vehicle has now been at the selling dealership for nearly one month while technicians attempt to diagnose and repair the issue. To date, I have not been provided with a definitive root cause or a permanent corrective action. The lack of resolution, combined with the recurring nature of the defect, has resulted in a complete loss of confidence in the vehicle's safety and reliability. My concerns are heightened by information suggesting that similar issues may have been experienced by owners of comparable GMC Sierra vehicles. Regardless of the ultimate root cause, the fact remains that my truck has repeatedly exhibited a condition that can unexpectedly disable the vehicle while in motion, creating an unacceptable safety hazard. I purchased this truck with the expectation that it would provide safe, dependable transportation. Unfortunately, after four loss-of-power events and an extended period in the repair facility without a successful resolution, I no longer believe this vehicle can safely fulfill that purpose.
2026 GMC Sierra 1500: sudden loss of power
15 of the 150 complaints about the 2026 GMC Sierra 1500 describe sudden loss of power.
- owner complaints
- 15
- of this car's complaints
- 10%
- recalls
- 0
Sudden loss of power by model year
What owners say
The vehicle lost power after sitting for a week. start up with a jump, but the battery doesn't hold a charge after that.
The 6.2L L87 V8 engine in my 2026 GMC Sierra 1500 suffered a sudden, catastrophic mechanical failure and shut down completely while driving at 65 mph with only 6113 miles on the odometer. There were no dashboard warning lights prior to the seizure, resulting in a sudden and dangerous loss of power. I was towing a 30 foot camper at the time and passing an 18 wheeler, it was truly a dangerous situation at the time and my wife and I feel very fortunate that we that we didn’t have a fatal accident.The dealership confirmed a total engine failure/seizure and had to replace the entire engine assembly under warranty."
Was driving the vehicle and started making a loud knocking noise and had a loss of power.
What component or system failed or malfunctioned, and is it available for inspection upon request? The truck has lost power unexpectedly while driving, and lately I've also noticed some lag when I accelerate. The truck is available to be inspected. How was your safety or the safety of others put at risk? The truck suddenly lost power while I was driving and told me to restart the vehicle. Losing power unexpectedly almost caused me to get stuck in an intersection and could have caused an accident in a busy shopping center. Has the problem been reproduced or confirmed by a dealer or independent service center? No. I took it to the GMC dealership after the second time it happened, but they couldn't get it to do it again and said there were no codes showing. They told me to bring it back if it happens a third time. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? Yes. I took it to the GMC dealership to have it checked after the second power-loss issue happened. Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? When it lost power, the truck prompted me to restart the vehicle. I have also recently started noticing some lag when accelerating and starting the vehicle. There was no warning before it happened.
Truck milage at the time of engine failure was 9,101. Well past the break in period for towing. We were towing a car trailer 2,000 pounds less the max towing capacity for the truck and going less than the posted speed limit. The truck was also in tow haul mode. The truck dash flashed oiled heating hot. We tried to pull over on the highway then the truck lost all power and overheated. Our trailer was not all the way off the highway, so a WY State Trooper pulled behind us and kept his lights flashing for 3 hours until a tow truck came. Truck could not be placed in neutral, so it had to be dragged onto the flat bed ramp of the tow truck. Truck was towed to the Gillette WY GMC dealership that same day. On Monday we were informed that the engine failed and needed to be totally replaced. The GM dealer cannot tell us how long it will take to get the new engine or how long we will be without the truck. This is the 6.2 V8 which GM assured buyer's of 2026 vehicles that the engine failures reported on previous year vehicles had been rectified on the new models. Less than 10,000 and the engine failed.
The contact owns a 2026 GMC Sierra 1500. The contact stated that while driving 45 MPH and depressing the accelerator pedal, the vehicle slowed down unexpectedly. The vehicle then lost power while stopped at a traffic light. No warning light was illuminated. The vehicle was turned off and restarted, and the vehicle operated as intended. The vehicle was taken to the dealer, where it was diagnosed and determined that there were metal shavings inside the oil pan and the engine needed to be replaced. The engine was replaced twice. The manufacturer was not notified of the failure. The approximate failure mileage was 3,202.
I am submitting this complaint to report what I believe is a serious safety-related defect involving the General Motors 6.2L L87 V8 engine installed in my 2026 GMC Sierra Denali. On July 10, 2026, while driving on a public highway near Bogata, Texas, the engine suddenly began making severe mechanical noises before catastrophically failing without warning. The engine seized completely while the vehicle was in motion. At the time of failure, the truck had only 13,517 miles. The sudden loss of engine power left my wife and me stranded on the roadside. Had this occurred while crossing an intersection, merging into traffic, passing another vehicle, towing a trailer, or traveling in heavier traffic, the consequences could have been far more serious.
While driving vehicle the engine lost power and shut off in traffic. There were no warning signs of issues at that time. The dashboard went blank and then reappeared and the truck was in park. after that the truck would not shift gears. The truck was towed to the dealership and found to have had catastrophic engine failure.
2026 GMC Sierra 1500 AT4X with 3898 miles. Driving 71mph on state highway on flat grade road. Lost power and vehicle shut down after pulling off the road. No previous lights or warning signs prior to power loss. Vehicle would not start afterwards. OnStar Diagnostics sent ECM Engine and Transmission System code P0016. Had vehicle towed 100miles to GM dealership. Upon inspection of vehicle, the Service Department contacted me the following day and said the the vehicle needed an entire engine replacement according to GM cooperate. I asked if it had anything to do with the 6.2L V8 L87 engine problems from previous recall years of 2021-2024. Service tech stated yes it was more than likely the same issue. Very unhappy with my new GM vehicle purchase. Will have to have a full engine replacement BEFORE my first oil change!
I was driving on interstate 95 at approximately 70 to 75 mph when I lost all power and compromise steering with tractor trailer behind me God willing I was able to pull over to the shoulder. My safety was compromised and I lost all faith in Gmc. My vehicle has been out of service for 27 days at this point while waiting for an engine replacement with no ETA on service. According to Pennsylvania lemon law after 30 days a lemon law claim can be submitted
Total engine failure on 5/31/26. Truck lost engine power while on highway and had to be towed to dealership where they found the lower end of the engine failed. Engine and radiator replacement needed, both are backordered with no eta.
Service bulletins that may apply
Related recalls
No recalls on record for this model year.
Questions about the 2026 GMC Sierra 1500 loss of power
Is sudden loss of power a common problem on the 2026 GMC Sierra 1500?
15 of 150 owner complaints about the 2026 GMC Sierra 1500 (10%) mention sudden loss of power. The model year with the most reports is 2019.
Is there a recall or service bulletin for this on the 2026 GMC Sierra 1500?
There are 0 recalls and 3 service bulletins for the same area of the car. Check them below with your VIN.
Other symptoms on the 2026 GMC Sierra 1500
Engine failure 53Check engine light 16Knocking 14Stalling 8Won't start 8Won't shift 6Hesitation 5
VIN decoder
See the problems and recalls for an exact car
Buying a used 2026 GMC Sierra 1500?
Check the exact car before you pay: accidents, salvage or flood titles, odometer readings and previous owners.
Check its history