Oxygen Sensor: Testing and Inspection

1. Start the engine and allow it to reach operating temperature.
2. Disconnect the oxygen sensor from the wire harness and connect a high impedance (greater than 1 Meg ohm input impedance) voltmeter between the oxygen sensor output connector and ground.
3. Increase engine rpm to approximately 1,500 rpm.
4. After approximately 70 seconds of operation at elevated rpm measure the output voltage of the oxygen sensor while changing engine rpm up and down slightly.
5. A properly operating oxygen sensor voltage signal should fluctuate between approximately 0.1 VDC and 0.9 VDC.
6. If voltage output is low or non-existant replace the oxygen sensor.

CAUTION! When replacing the oxygen sensor exercise great care to prevent ANY trace of silicone compounds from contaminating and thereby destroying the oxygen sensor. Such compounds include; anti-freeze, silicone based lubricants, and silicone (RTV) sealants.