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 is operating.
The ignition 1 voltage is more than 10.5 volts.
The HO2S heater is at operating temperature for more than 10 seconds.
The calculated exhaust temperature is between 250-800° C (482-1,472° F).
DTC P0138 runs continuously once the above conditions are met for more than 90 seconds.