Conditions for Setting the DTC
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
The PCM detects that the 02 Heater Current parameter is less than 0.25 A or more than 0.90 A for longer than 3 minutes and 10 seconds.