Conditions for Running the DTC

WARNING: This page is about a different car, the 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

DTCs P0601, P0602, P0604, P0606, P1621, and P2610 are not set.
The ignition is in unlock, accessory, run, or crank mode.
The ignition voltage is greater than 5.2 volts.
DTC P0651 runs continuously when the above conditions are met.