Conditions for Running the DTC

WARNING: This page is about a different car, the 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

P0627 and P0629

The engine speed is greater than 80 RPM.
The ignition voltage is between 10-18.1 volts.
The ECM has commanded the fuel pump relay OFF.
The above conditions are met for greater than 1 second.
The DTCs run continuously once the above conditions are met.

P0628

The engine speed is greater than 80 RPM.
The ignition voltage is between 10-18.1 volts.
The ECM has commanded the fuel pump relay ON.
The above conditions are met for greater than 1 second.
The DTC runs continuously once the above conditions are met.