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.

The battery voltage is more than 5.23 volts.
DTCs P0641, P0651, P2120, or P2125, are not set.
DTC P2138 runs continuously when the above conditions are met.