Oxygen Sensor: Testing and Inspection

Fig. 24 Connecting voltmeter to oxygen sensor.:

1. Warm up engine and run at idle.
2. Disconnect oxygen sensor wiring harness connector.
3. Attach voltmeter between oxygen sensor connector (oxygen sensor side) and ground Fig. 24.
4. Measure voltage with throttle valve fully open and closed. There should be more than .6 volt with throttle valve fully open and zero to .4 volt with throttle valve fully closed.
5. If voltage is not as described, replace oxygen sensor.
6. Check sensitivity of oxygen sensor as follows:
a. With engine idling at operating temperature, connect system tester to check connector.
b. Increase engine speed to between 2000---3000 RPM and ensure monitor lamp flashes more than 8 times in 10 seconds.