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)

3 of 49 complaints match · Driver assistance · clear filters

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 15, 2024Electrical systemEngineDriver assistance

Smog system check and Engan warning light keeps come on.

NHTSA ODI 11608733

Feb 28, 2021EngineBackup camera & sensorsDriver assistance

THE TRUCK IS PARKED AT DEALERSHIP

NHTSA ODI 11398288

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 →