2020 GMC Sierra Service and Repair Manual
This factory service and repair manual for the 2020 GMC Sierra covers four trims, AT4, AT4 CarbonPro, Denali and Regular, and two body styles, the four-door crew cab pickup and the two-door standard cab. The engine list holds the 325-cubic-inch 5.3L V8 and the 376-cubic-inch 6.2L V8, both gasoline, naturally aspirated and overhead-valve. Specifications, torque values, wiring diagrams and diagnostics follow each system through those configurations rather than treating the trims as separate machines.
Engines covered
- 5.3L V8 (325 cu in) — OHV, naturally aspirated, gasoline
- 6.2L V8 (376 cu in) — OHV, naturally aspirated, gasoline
Body styles covered
- 4-door crew cab pickup
- 2-door standard cab pickup
Trims covered
- AT4
- AT4 CarbonPro
- Denali
- Regular
Known issues on the 2020 Sierra. Eight recalls have been issued against this year. Some fuel pumps left the line without a pressure regulator, which lets fuel system pressure climb until the pump cracks and leaks. Roof-rail air bag inflators could have a poorly crimped diffuser that separates during deployment and degrades how the bag performs. Battery positive cable rings assembled with excess glue could make an intermittent connection at the alternator and stall the truck. Complaints stand at 456: 154 against the engine, 88 against the power train and 50 against the electrical system.
