Test Description

The numbers below refer to the step numbers in the diagnostic procedures.

1. 2  - HO2S 2 should be allowed to cool before performing this test. HO2S 2 is cool enough if voltage output is stable at bias or about 450 mV. If HO2S 2 heater is functioning, signal voltage will gradually change as sensor element warms. If heater is not functioning, HO2S 2 signal will remain near 450 mV bias voltage or show very little activity.
2. 4  - This step ensures that ignition voltage circuit to HO2S 2 is not open or shorted. Test light must be connected to a good ground, independent of HO2S system.
3. 6  - This test must not be performed until HO2S 2 heater has cooled and stabilized for at least 15 minutes. Heater resistance is typically about 5 ohms at room temperature.