Detection Condition

WARNING: This page is about a different car, the 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

PCM monitors input voltage from front HO2S when following monitoring conditions are met. If input voltage from sensor never exceeds 0.55 volt for 83.2 seconds, PCM determines HO2S sensor circuit is not activated.

Monitoring Conditions:

MODE 3 - HO2S Heater, HO2S & TWC Repair Verification Drive Mode.
Engine speed is more than 1500 RPM.
Engine coolant temperature is more than 176°F (80°C).

This is a Continuous Monitor (CM). MIL illuminates if PCM detects malfunction condition in two consecutive drive cycles or in one drive cycle while DTC for same malfunction has been stored in PCM. PENDING CODE is available if PCM detects malfunction condition during first drive cycle. FREEZE FRAME DATA is available. DTC is stored in PCM memory.