2020 GMC Sierra 3500 power train problems
19 owner complaints filed with NHTSA name the power train on the 2020 GMC Sierra 3500 — 37% of all complaints for this model year.
What owners report
“My truck has been exhibiting hard downshifting at certain speeds, when the powertrain loads up such as a grade change, and requires a downshift. I have complained about this issue to the dealership as early as 2022, and 33,185 miles. The dealership made me pay for a transmission $388.90 flush which…”
filed Mar 20, 2026
“The contact owns a 2020 GMC Sierra 3500. The contact stated that while driving at an undisclosed speed, the vehicle inadvertently went into LIMP Mode. There was no warning light illuminated. The vehicle was taken to the dealer, where it was diagnosed that the transmission valve body sensor had…”
filed Jul 9, 2025
Verbatim excerpts from complaints filed with NHTSA. Reports are not independently verified.
Related recalls
- Transmission control valve may fail and cause the rear wheels to lock upCampaign 26V083000 · Feb 12, 2026
- Transmission control valve may fail and cause the rear wheels to lock-upCampaign 24V797000 · Oct 24, 2024
Power Train problems in other Sierra 3500 years
| Year | Reports | Share |
|---|---|---|
| 2024 Sierra 3500 | 12 | 28% |
| 2023 Sierra 3500 | 14 | 50% |
| 2022 Sierra 3500 | 5 | 17% |
| 2021 Sierra 3500 | 7 | 35% |
| 2016 Sierra 3500 | 2 | 11% |
| 2015 Sierra 3500 | 1 | 3% |
| 2011 Sierra 3500 | 2 | 10% |
| 2008 Sierra 3500 | 1 | 4% |
| 2004 Sierra 3500 | 1 | 4% |
| 2000 Sierra 3500 | 3 | 12% |
Other reported problem areas on the 2020 GMC Sierra 3500
Counts are unique NHTSA complaints naming this component group. Complaints are unverified owner reports; mileage is computed only from complaints that included a usable odometer reading.