Most common 2020 GMC Sierra problems
Share of the 11 complaints; one complaint can involve more than one system. "~" is the median mileage when the problem started.
GMC Sierra complaints by model year
Best Sierra years: 2020, 2018, 2009. Years to avoid: 1999, 2000, 1995, 1996, 1997. Compare all years →
What 2020 GMC Sierra owners say
Engine & cooling
The contact owns a 2020 GMC Sierra Denali. The contact stated that while stopped at a traffic light with the brake pedal depressed, the vehicle shut off unexpectedly. There was no warning light illuminated. The contact made several attempts to restart the vehicle; however, the vehicle failed to restart. Due to the failure, the vehicle was towed to the dealer where a diagnostic test was performed. The contact was later informed that the engine had seized due to engine bearing failure, and the contact was provided an estimate for a new engine. Upon investigation, the contact discovered NHTSA Campaign Number: 25V274000 (Engine and Engine Cooling) and linked the recall to the failure. The manufacturer was notified about the failure and the recall, and the contact was informed that the VIN was not included in the recall. The vehicle was not repaired and remained with the dealer. …
The contact owned a 2020 GMC Sierra Denali. The contact stated that while the vehicle was parked, there was an abnormal knocking sound coming from the engine compartment. The check engine warning light was intermittently illuminated. The vehicle was taken to a dealer; however, the cause of the failure was not yet determined. The dealer advised the contact to purchase a new vehicle because the engine would eventually need to be replaced. The contact stated that at approximately 3,000 miles, there was an abnormal odor oil burning odor coming from the vehicle. The contact stated that the vehicle was consuming an excessive amount of engine oil and approximately 5 quarts needed to be added between scheduled oil changes. The failure mileage was approximately 25,000.
2020 GMC Sierra engines & fuel economy
| Engine | Transmission | Drive | MPG city / hwy / combined |
|---|---|---|---|
| 3.0L 6-cyl turbo diesel | 10-speed automatic | RWD | 23 / 30 / 26 |
| 3.0L 6-cyl turbo diesel | 10-speed automatic | 4WD | 22 / 26 / 24 |
| 2.7L 4-cyl turbo | 8-speed automatic | RWD | 20 / 23 / 21 |
| 5.3L 8-cyl | 8-speed automatic | RWD | 17 / 24 / 20 |
| 2.7L 4-cyl turbo | 8-speed automatic | 4WD | 19 / 22 / 20 |
| 5.3L 8-cyl | 10-speed automatic | 4WD | 16 / 22 / 19 |
| 5.3L 8-cyl | 8-speed automatic | 4WD | 16 / 22 / 18 |
| 4.3L 6-cyl | 6-speed automatic | RWD | 16 / 21 / 17 |
| 5.3L 8-cyl | 6-speed automatic | RWD | 15 / 21 / 17 |
| 6.2L 8-cyl | 10-speed automatic | 4WD | 15 / 20 / 17 |
| 5.3L 8-cyl | 6-speed automatic | 4WD | 15 / 20 / 17 |
| 4.3L 6-cyl | 6-speed automatic | 4WD | 15 / 20 / 17 |
EPA ratings. Class: Full-size pickup.
Frequently asked questions
Is the 2020 GMC Sierra a good car?
Based on 11 owner complaints filed with NHTSA, the 2020 Sierra rates better than average: 83% fewer complaints than a typical year of the Sierra at the same age. It is one of the best Sierra years by this measure. Complaint counts don't account for sales volume or individual maintenance, so have any used car inspected before buying.
What is the most common problem with the 2020 GMC Sierra?
The engine & cooling — 7 complaints, 64% of all complaints for this model year. Next are the brakes (2) and driver assistance (2).
How many recalls does the 2020 GMC Sierra have?
NHTSA lists no recalls for the 2020 GMC Sierra. You can still confirm with your VIN using our VIN recall check.
What are the best and worst years of the GMC Sierra?
The best years by complaints, compared at the same age, are 2020, 2018 and 2009. Years to avoid or approach with caution: 1999, 2000, 1995, 1996 and 1997. See the full GMC Sierra years comparison.
At what mileage do 2020 GMC Sierra problems happen?
The median mileage reported in complaints is about 20,000 miles; 67% of problems with a recorded mileage started before 50,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.