WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
If DTCs C0300 or C0305 have set, diagnose these DTCs first as they may cause DTC C0374 to set falsely. Refer to DTC C0300 or DTC C0305 .