2021 GMC Sierra 3500: Problems & Reliability
SOLID2021 GMC Sierra 3500: SOLID — 20 owner complaints, a typical complaint rate for ~5 years on the road; top issue: powertrain / transmission (7 complaints).
CarWhere's verdict score for the 2021 is 1.11, where 1.00 is a typical Sierra 3500 year once complaints are weighted for severity and spread over time on the road, between the best line (0.75) and caution (1.25). Severity drives it: 65% of those complaints report a crash, fire or injury or involve a safety-critical system (engine, powertrain, steering, brakes or fuel).
Sources: NHTSA owner complaints (ODI), recall campaigns and manufacturer service bulletins, CarWhere verified buyer prices · Model years 2015–2026 compared · Updated 2026-11-07 · By CarWhere Research · Methodology
20
NHTSA complaints
1.11
Verdict score (1.00 = typical Sierra 3500 year)
827
Service bulletins
5
Recall campaigns
Most-reported 2021 GMC Sierra 3500 problems
Powertrain / transmission is the clear leader, named in 35% of complaints.
| Component | Complaints | Share of 2021 complaints |
|---|---|---|
| Powertrain / transmission | 7 | 35% |
| Service brakes | 5 | 25% |
| Electrical system | 4 | 20% |
| Unknown or other | 3 | 15% |
| Engine | 3 | 15% |
A complaint can name more than one component, so shares can add up to more than 100%.
2021 GMC Sierra 3500 recalls
5 recall campaigns on federal record for the 2021, reported between Dec 17, 2020 and Oct 24, 2024.
| NHTSA campaign | Reported | Component |
|---|---|---|
| 24V797000 | Oct 24, 2024 | Powertrain / transmission › Automatic transmission › Control module › Software |
| 24V060000 | Feb 1, 2024 | Latches, locks & linkages › Tailgate › Latch |
| 21V758000 | Sep 29, 2021 | Service brakes, hydraulic › Power assist › Electric › Control module |
| 20V811000 | Dec 23, 2020 | Seat belts |
| 20V792000 | Dec 17, 2020 | Seat belts |
2021 GMC Sierra 3500 service bulletins
The manufacturer has filed 827 technical service bulletins with NHTSA for the 2021 — close to the 735 of the median Sierra 3500 year from 2015 to 2026. Coded bulletins most often cover electrical system (209), engine & cooling (172), powertrain / transmission (116). Bulletins are repair instructions for dealer technicians, not recalls.
The 2021 vs. the year before and after
From the 2020 to the 2021, owner complaints fell by more than half (45 → 20) — an improvement. The 2022 that followed rose 60% (20 → 32), so the 2021 is the cleaner of the two by count.
| Model year | Verdict | Complaints | Bulletins | Recalls | Avg. buyer-paid |
|---|---|---|---|---|---|
| 2020 Sierra 3500 | AVOID | 45 | 895 | 8 | — |
| 2021 (this page) | SOLID | 20 | 827 | 5 | — |
| 2022 Sierra 3500 | CAUTION | 32 | 879 | 3 | — |
Prices are averages of CarWhere verified buyer transactions (shown when 3+ deals exist for the year). Full year-by-year table: GMC Sierra 3500 years to avoid.
What to check on a used 2021 GMC Sierra 3500
Powertrain / transmission (7 complaints on the 2021): test-drive from cold through every gear and feel for slipping, harsh or delayed shifts and shudder; ask whether the transmission fluid has been serviced.
Service brakes (5 complaints on the 2021): check pedal feel, pulling and grinding, look at rotor and pad wear, and ask when the brake fluid was last changed.
Electrical system (4 complaints on the 2021): test every light, window, lock, the infotainment screen and the charging system, and have the car scanned for stored fault codes.
Engine (3 complaints on the 2021): cold-start it yourself and listen for ticking or knocking; check for oil leaks, low coolant and a lit check-engine light, and ask for oil-change records.
Fuel / propulsion system (2 complaints on the 2021): smell for fuel around the car, watch for hesitation or stalling, and check for a lit check-engine light.
Recalls: confirm all 5 campaigns above were completed on this VIN.
Know what to pay for the right 2021 GMC Sierra 3500 — then negotiate it
Years-to-avoid tells you which year. Search live listings to see the target price and what verified buyers actually paid for it.
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FAQ
Is the 2021 GMC Sierra 3500 reliable?
2021 GMC Sierra 3500: SOLID — 20 owner complaints, a typical complaint rate for ~5 years on the road; top issue: powertrain / transmission (7 complaints). CarWhere's verdict score for the 2021 is 1.11, where 1.00 is a typical Sierra 3500 year once complaints are weighted for severity and spread over time on the road, between the best line (0.75) and caution (1.25).
What are the most common 2021 GMC Sierra 3500 problems?
By NHTSA owner complaints, the most-reported areas on the 2021 GMC Sierra 3500 are powertrain / transmission (7, 35%), service brakes (5, 25%), electrical system (4, 20%). The manufacturer has 827 service bulletins on file for this model year.
How many recalls does the 2021 GMC Sierra 3500 have?
5 recall campaigns on federal record for the 2021 GMC Sierra 3500, most recently 24V797000 (Oct 24, 2024, powertrain / transmission); 24V060000 (Feb 1, 2024, latches, locks & linkages); 21V758000 (Sep 29, 2021, service brakes, hydraulic). Recall completion is VIN-specific, so check the exact car.
How do I check a specific 2021 GMC Sierra 3500 before buying?
Decode the VIN free at carwhere.com/tools/vin-decoder to confirm the build, then run the $9.99 CarWhere Full VIN Report for the exact VIN — recall, complaint, and service-bulletin record for this model year, the original window sticker where the manufacturer publishes one, and a market price check from verified buyers. One-time purchase, no subscription.
Sources & method
Complaint, recall and service-bulletin counts for the 2021 GMC Sierra 3500 come from NHTSA's Office of Defects Investigation; the verdict is CarWhere’s severity-weighted, time-on-road-adjusted score compared with the model’s own median year. Complaints are owner allegations, not verified defects. Full methodology.