GMC Sierra Owners Manual
California Fuel Requirements
If the vehicle is certified to meet California Emissions Standards, it is designed to operate on fuels that meet California specifications. See the underhood emission control label. If this fuel is not available in states adopting California Emissions Standards, the vehicle will operate satisfactorily on fuels meeting federal specifications, but emission control system performance might be affected. The malfunction indicator lamp could turn on and the vehicle might fail a smog-check test.
See Malfunction Indicator Lamp on page 5‑25. If this occurs, return to your authorized dealer for diagnosis.
If it is determined that the condition is caused by the type of fuel used, repairs might not be covered by the vehicle warranty.