Conditions for Running the DTC

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

DTCs P0601, P0602, P0604, P0606, P1516, P2108, U0107 are not set.
DTCs P0120 and P0220 are not active at the same time.
The ignition switch is in the Crank or Run position.
The ignition voltage is more than 8.5 volts.
The TAC system is not in the battery saver mode.