HO2S Warm-Up Sensor 1 / HO2S Warm-Up Sensor 2

The scan tool range is 00:00 to 99:99 MIN:SEC. This indicates the time to warm-up for each HO2S. The HO2S warm up time is used for the HO2S heater test. The PCM runs the heater test only after a cold start (determined by engine coolant and intake air temperature at the time of startup) and only once during an ignition cycle. When the engine is started the PCM monitors the HO2S voltage. When the HO2S voltage indicates a sufficiently active sensor, the PCM looks at how much time has elapsed since startup. If the PCM determines that too much time was required for the HO2S to become active, a DTC is set. If the engine was warm when started, HO2S Warm-Up displays the value that was stored the last time the test ran. If the information is cleared, HO2S Warm-Up displays 00:00.