Conditions for Setting the DTC
WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
The ECM detects that the HO2S 2 voltage is greater than 630 mV for greater than 100 seconds, then an intrusive test is performed. The ECM will lean the fuel mixture -2 percent per second and then wait for 10 seconds at -15 percent. If the ECM detects that the HO2S voltage is still greater than 630 mV, for 4 seconds or for a cumulative of 30 seconds the DTC sets.