Oxygen (O2) Sensor
CAUTION:
Do not attempt to measure O2 sensor output voltage with a conventional voltmeter. Current drain of voltmeter could damage sensor. Oxygen sensor voltage signal can be measured using a 10-megohm (minimum input impedance) digital voltmeter.
- Start engine and warm to operating temperature. Ensure vehicle is operating in closed loop. Unplug O2 sensor connector at sensor.
- Using DVOM (digital volt/ohmmeter) with a minimum 10-megohm imput impedance, connect DVOM (on voltmeter scale) between ground and oxygen sensor connector (sensor side).
- Place a short jumper wire in sensor lead (computer side). While holding jumper wire in one hand, alternately touch battery negative terminal and then positive terminal with other hand. DO NOT TOUCH sensor lead directly to battery.
- Monitor DVOM reading. When negative terminal of battery is touched, oxygen sensor output voltage should increase (up to one volt). When positive terminal of battery is touched, oxygen sensor output voltage should drop (as low as .1 volt).
- If oxygen sensor does not respond as indicated, replace sensor.
NOTE:
O2 sensor problems may set a Code 13. For more O2 sensor testing procedure, refer to TESTS W/CODES - EFI
article.