Conditions For Setting DTC
WARNING: This page is about a different car, the 2002 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
If the AIR pump turns ON during a closed loop operation and the HO2S voltage does not fall below 222 mV for 1.3 seconds; or if the AIR pump turns ON during a closed loop operation and the short-term fuel trim does not change more than a predetermined amount.