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 HO2S 1 rich-to-lean transition time takes longer than 280 milliseconds.
OR
The PCM detects that the HO2S 1 lean-to-rich transition time takes longer than 210 milliseconds during a 90 second monitoring period.