2021 Gmc SIERRA 3500 problems and owner complaints
Explore the records behind recurring owner reports.
Key facts
20 owner complaints analyzed
5 distinct recall campaigns
101,500 mi median reported failure mileage
Scope: 2021 model year. Data snapshot: . 4 complaints include usable failure mileage.
Most common problems
Power Train is the most frequently named component, appearing in 7 of 20 complaints (35.0%). A complaint can name multiple components.
| Topic | Matching reports | Share of complaints |
|---|---|---|
| Transmission and shifting | 5 | 25.0% |
| Braking behavior | 4 | 20.0% |
| Electrical and battery issues | 2 | 10.0% |
Topic matches use published keyword rules. They describe mentions, including negations or comparisons, and do not confirm a diagnosis. Read the matching rules.
Component breakdown
Number of unique complaints naming each component. Top eight shown.
| Category | Count |
|---|---|
| Power Train | 7 |
| Service Brakes | 5 |
| Electrical System | 4 |
| Engine | 3 |
| Unknown Or Other | 3 |
| Fuel/Propulsion System | 2 |
| Back Over Prevention | 1 |
| Structure:Body | 1 |
Power Train: 7; Service Brakes: 5; Electrical System: 4; Engine: 3; Unknown Or Other: 3; Fuel/Propulsion System: 2; Back Over Prevention: 1; Structure:Body: 1
Reported problems by failure mileage
Complaint counts in mileage bands. These are not failure rates per vehicle or mile.
| Category | Count |
|---|---|
| Under 25,000 | 0 |
| 25,000 to 49,999 | 1 |
| 50,000 to 74,999 | 1 |
| 75,000 to 99,999 | 0 |
| 100,000 to 149,999 | 2 |
| 150,000 and above | 0 |
Under 25,000: 0; 25,000 to 49,999: 1; 50,000 to 74,999: 1; 75,000 to 99,999: 0; 100,000 to 149,999: 2; 150,000 and above: 0
100,000 to 149,999 miles has the most reports with usable mileage (2). 16 complaints have missing, zero or invalid mileage.
Complaints over time
Year the complaint was filed, not the vehicle model year or incident year. The snapshot year is partial.
| Category | Count |
|---|---|
| 2021 | 2 |
| 2022 | 5 |
| 2023 | 1 |
| 2024 | 3 |
| 2025 | 8 |
| 2026 | 1 |
2021: 2; 2022: 5; 2023: 1; 2024: 3; 2025: 8; 2026: 1
Pattern summary
Power Train leads the component reports. Transmission and shifting appears in 5 complaint narratives. Braking behavior appears in 4 complaint narratives. Electrical and battery issues appears in 2 complaint narratives. Use these patterns to inspect individual reports and prepare questions for a mechanic.
Calculated from recorded counts. An AI narrative has not been published for this selection.
Complaint evidence
Examples provide context, not a representative sample or a verified diagnosis.
Owner report 11459426 · 2022-04-03 (April 3, 2022)
Problem: Unable to shift transmission from D to another position like R, P, N due to snow/slush being on shifter. I travel on Idaho state highways and County roads that are plowed. In February, I traveled state highway 14. Road conditions were plowed snow roads, broken snow floor, slush and pavement without slush or snow. I had a passenger with me on this trip from Elk City, Idaho to Grangeville, Idaho via SH-14. When I pulled into my storage unit, I could not shift from D to P or N or R. I could only drive forward. The temperature in Gra…
Owner-reported narrative. Look up ODI 11459426 at NHTSA ↗
Owner report 11617429 · 2024-10-01 (October 1, 2024)
While driving 55mph on a 2 lane road, pulling a 5th wheel camper, the truck transmission downshifted by itself to a low gear. This caused a scary and immediate deceleration from 55 to 25mph. The trailer wanted to push into the oncoming lane the deceleration was so fast. The truck is at a dealership and they acknowledge the issue but not a fix other than putting back in the failed part. There was no warning and my readings say many others are having same issue. The small dealership we left the truck with (yemm Chevrolet in Galesburg Il) said t…
Owner-reported narrative. Look up ODI 11617429 at NHTSA ↗
Owner report 11420443 · 2021-06-10 (June 10, 2021)
Trailer brake wiring connection continually disconnectsthen reconnects some time later. Some periods of up to 10 minutes without having trailer braking power. Major safety issue when toeing fifth wheel trailer. We lost brakes going down steep grades. GMC is aware of issue, but has not provided a solution. Vehicle has been yo service shop with no resolution. Case has been opened with GMC.
Owner-reported narrative. Look up ODI 11420443 at NHTSA ↗
Owner report 11438295 · 2021-10-26 (October 26, 2021)
The vehicle recently had a recall repaired at the dealership. I subsequently took delivery on it as a BRAND NEW UNIT, and the brakes are extremely soft; to the point where I must depress the pedal to the floor to get it stopped even at slow speeds. I hoped it was just an air bubble from the repair; but the fluid levels are full and the dealer had no ideas on what could be wrong at this point. I have a great relationship with this dealer, and we’ll continue working on it. But GM is releasing absolute trash lately and I fear that some poor fami…
Owner-reported narrative. Look up ODI 11438295 at NHTSA ↗
Owner report 11623109 · 2024-11-01 (November 1, 2024)
Multiple instances of diesel engine emissions system parts and software failure. While driving, towing or not, the DIC would randomly display a message that the DEF level is low and reduced speed will occur in x-amount of miles and that mileage would then begin a visible countdown on the DIC, sometimes much more quickly than the actual speed I was traveling. In other words, it might at first state 500 miles remaining, but then be counting down from 500 miles by one mile per second of time, or faster. Each instance, I would park and attempt to r…
Owner-reported narrative. Look up ODI 11623109 at NHTSA ↗