Test Description

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

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