Home · 2021 GMC Sierra 2500 Hd · Complaints

What 49 owners told NHTSA about the 2021 GMC Sierra 2500 Hd

These are the actual owner complaints behind this car’s reliability verdict, filed with the federal government, unedited. They’re unverified reports, not confirmed defects: read them as leads for your pre-purchase inspection, not a diagnosis.

All (49)Crash / fire / injury (4)Transmission & drivetrain (12)Lights (9)Engine (8)Electrical system (6)Body & structure (5)Brakes (5)Latches & locks (4)Driver assistance (3)Airbags (2)Backup camera & sensors (1)

4 of 49 complaints match · crash/fire/injury only · clear filters

Oct 29, 2025Transmission & drivetrainCrash1 injury

The contact owns a 2021 GMC Sierra 2500. The contact stated that while driving at 50 MPH, the contact was pulling a trailer that he had loaded, and he drove around a curve, the gear shifted down independently, and the trailer pushed the vehicle off the right side, causing him to crash into a post and embankment. The contact mentioned he was able to shift the gear into Four Wheel Drive to get back on the road. The contact mentioned he pulled over to the right side of the road, exited the vehicle to inspect, and noticed damage to the vehicle and the trailer. The contact stated no air bag deployed. The contact stated that he sustained injuries left arm and neck, causing his muscles to tighten. No medical attention was required. The contact stated no police report was filed. The contact mentioned that the vehicle was previously repaired for a manufacturer's recall with the transmission, but failed to prevent the failure. The contact was relating the failure to NHTSA Campaign Number: 24V797000 (POWER TRAIN). The vehicle was serviced by the dealer, but the remedy failed to repair the vehicle. The contact stated that the failure was not diagnosed by a dealer or independent mechanic. The manufacturer was not notified of the failure. The approximate failure mileage was 78,000.

NHTSA ODI 11696338

Sep 11, 2025Electrical systemCrash

When I’m in reverse the up the cameras turn off. On one incident I was backing up and the camera turned off causing me to back up into the wall of my house

NHTSA ODI 11686699

Nov 5, 2024Driver assistanceCrash

I purchased a 2021 GMC Denali 2500 in December 2023. A couple days after purchasing the vehicle I received a message on the dash saying the front camera was not working. I took the vehicle into the dealership where they said they reset the computer and nothing was wrong with the vehicle. One month later I was involved in a collision where a vehicle turned in front of my vehicle and the Automatic Emergency Braking failed to activate. I applied the brakes but due to my delayed reaction time 1.5 seconds, I broadsided the small vehicle with my large truck. Luckily the speed was only 20 mph and no one was hurt or killed. At this time I did not know my vehicle was equipped with AEB. In October I discovered through GM and a different dealership that my vehicle was equipped with Automatic Emergency Braking. I have had several occasions when the AEB including the crash where the AEB should have activated but never did. In 11 months I have never had the AEB activate. I took the vehicle into the dealership where I bought the vehicle and they said their computer said everything was operating correctly. The tech never drove the vehicle where the AEB should have activated. I have driven many cars and even the same model vehicle as mine, so I know what the AEB feels like and my vehicle the AEB is not working. The dealership told me to take the vehicle they checked everything GM told them to check. When I talked to GM they told me to immediately take the truck to the dealership and the dealership did nothing.

NHTSA ODI 11623737

Aug 8, 2022AirbagsBody & structureCrashFire

Hit in the driver side tire, air bags didn’t release. Truck then went up in flames.

NHTSA ODI 11478289

Working with the data? Download all 49 complaints as CSV · fetched from NHTSA July 19, 2026

How to use these: a complaint is one owner’s report, filed voluntarily and published unverified. Patterns matter more than any single story. If several owners describe the same failure at similar mileage, put that system at the top of your pre-purchase inspection list. Back to the full 2021 GMC Sierra 2500 Hd verdict →