Conditions for Setting the DTC
WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.
The PCM detects that the HO2S 1 heater calculated resistance is not within an expected range at engine start-up for 1 second.