2021 GMC Sierra 2500 problems & reliability
51 owner complaints filed with NHTSA for the 2021 GMC Sierra 2500, alongside 6 safety recall campaigns. Last verified Aug 7, 2026. Complaints are unverified reports submitted by owners to the federal Office of Defects Investigation.
Each complaint is counted once (by NHTSA case number), even when it names several vehicles.
1 complaint report injuries (1 injured).
Most reported problems
| Component | Complaints | Share |
|---|---|---|
| Power Train → | 12 | 24% |
| Exterior Lighting | 9 | 18% |
| Engine | 8 | 16% |
| Electrical System | 6 | 12% |
| Service Brakes | 6 | 12% |
| Structure | 5 | 10% |
| Latches/locks/linkages | 4 | 8% |
| Forward Collision Avoidance | 3 | 6% |
| Unknown OR Other | 3 | 6% |
| Air Bags | 2 | 4% |
Component groups as classified by NHTSA. A complaint can name more than one component, so shares may sum to more than 100%.
Complaints by incident year
What owners report
“The left rear internal "top-hat" parking brake shoes suffered a total manufacturing bonding failure, causing the friction lining to completely delaminate and detach from the metal backing plates inside the rotor hub. This triggered Diagnostic Trouble Code (DTC) C060B (Left Park Brake Actuator Circuit). The failed…”
Service Brakes · filed Aug 5, 2026
“After finishing a long drive south, I shut the engine off and a yellow engine code popped on. I connected my computer to it and revealed a P129F code (fuel pump control module). I have noticed that other GMC models have been included in a recall concerning this problem. The 2021 GMC 2500 Denali should be also since it…”
Fuel/propulsion System · filed Jul 30, 2026
“I am reporting repeated failures involving both the transmission and diesel emissions (DEF) system on my 2021 GMC Sierra 2500HD Denali equipped with the 6.6L Duramax diesel engine and Allison 10-speed automatic transmission. While under warranty, the truck required replacement of the aftertreatment fuel injector and…”
Fuel/propulsion System · filed Jun 26, 2026
Verbatim excerpts from complaints filed with NHTSA. Reports are not independently verified.
Federal defect investigations
- Air Bag Malfunction
Preliminary Evaluation PE21010 · opened Apr 9, 2021 · closed Aug 24, 2023
Technical service bulletins
1,056 manufacturer communications (TSBs, service campaigns, warranty extensions) are on file with NHTSA for the 2021 GMC Sierra 2500. The 10 most recent:
This PI provides information to repair the door water deflector which is not sealed properly allows water into the door jam/sill area.
PIT5680B · Service Bulletin/Repair Instructions · issued Jul 23, 2026
PI to help diagnose A/C concern
PIT5099J · Service Bulletin/Repair Instructions · issued Jul 21, 2026
This PI provides diagnostic tips for diagnosing electric trailer brakes issues.
PIT5509N · Service Bulletin/Repair Instructions · issued Jul 21, 2026
This PI was created to help avoid unnecessary front camera module replacements
PIT6473F · Service Bulletin/Repair Instructions · issued Jul 17, 2026
The purpose of this PI is to inform dealer technicians of a normal cab pressure relief valve noise to avoid unnecessary part replacement
PIT6532 · Service Bulletin/Repair Instructions · issued Jul 6, 2026
This Preliminary information communicates information on a hydraulic rush type noise from the power steering gear. This noise is a characteristic of the new Active Hydraulic Assist System RPO NV8 and no repairs should…
PIT5544J · Service Bulletin/Repair Instructions · issued Jun 24, 2026
This Preliminary information communicates an issue with an OTA pending message still displayed after an OTA event and how to reset/clear the message.
PIT5966F · Service Bulletin/Repair Instructions · issued Jun 23, 2026
This PI provides diagnostic steps for dealer technicians to verify the condition and ensure that part replacement is necessary
PIT6523 · Service Bulletin/Repair Instructions · issued Jun 10, 2026
This Preliminary information communicates an issues with the HVAC making a hum buzz noise when the blower is set to a higher speed. Engineering is working on a new HVAC door seal material to correct the noise.
PIT6132E · Service Bulletin/Repair Instructions · issued Jun 9, 2026
This PI provides diagnostic tips for diagnosing electric trailer brakes issues.
PIT5509M · Service Bulletin/Repair Instructions · issued May 14, 2026
TSBs are repair guidance manufacturers send to dealers — they are not recalls and repairs are not automatically free. Full documents are available on NHTSA’s site.
Safety recalls
The 2021 GMC Sierra 2500 has 6 NHTSA recall campaigns — recall repairs are free at franchised dealers regardless of the vehicle’s age.
Check whether your specific vehicle is affected
Recall campaigns often cover only certain VIN ranges. Enter your VIN on the official NHTSA site to confirm whether your vehicle is included and whether the repair is still open.
Check VIN on NHTSA →Buying a used 2021 GMC Sierra 2500?
- · Decode the seller’s VIN with our free VIN decoder to confirm the exact year, engine and trim.
- · Check for unrepaired recalls by VIN on NHTSA’s official lookup — recall repairs are free.