Conditions for Running the DTC

WARNING: This page is about a different car, the 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

The engine speed is 0 RPM.
The ignition is ON, with the engine OFF.
The ignition 1 voltage is more than 10.5 volts.
The ECM has commanded the fuel pump relay ON and OFF at least once during the ignition cycle.
The above conditions are met for more than 1 second.
DTC P0627 runs continuously once the above conditions are met.