Conditions For Setting DTC
WARNING: This page is about a different car, the 2002 GMC Sonoma and 2002 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.
The HO2S voltage does not go greater than 600 millivolts or less than 300 millivolts within 110-255 seconds after cold start. Depending on driving conditions and start up coolant temperature.