Conditions for Running the DTC

WARNING: This page is about a different car, the 2009 GMC Sierra and 2009 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The ignition is in Unlock, Accessory, Run, or Crank.
The ignition voltage is more than 5.23 volts.
DTCs P0641 and P0651 run continuously when the above conditions are met.