Conditions for Setting the DTC (w/LLT)
WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
The ECM detects that the rear HO2S voltage is greater than 650 mV for greater than 100 seconds, then an intrusive test is performed. The ECM will lean the fuel mixture up to -7 percent and then wait for 10 seconds at -7 percent. If the ECM detects that the HO2S voltage is still greater than 650 mV, the ECM then tests the HO2S at the next decel fuel cut-off. If the ECM detects the HO2S voltage is greater than 200 mV after 4 seconds or for a cumulative of 50 seconds in decel fuel cut-off, the DTC sets.