Oxygen Sensor: Testing and Inspection

Fig. 24 Connecting voltmeter to oxygen sensor.:

1. Warm up engine & run at idle.
2. Disconnect connector at oxygen sensor wiring harness.
3. Attach a voltmeter between O2 sensor connector ( sensor side) and ground Fig. 24.
4. Run engine at 4000 RPM until voltmeter indicates approximately .7 volt.
5. Increase and decrease engine speed suddenly several times. When speed is increased, meter should read .5-1 volt. When speed is decreased, meter should read 0-.3 volt.
6. If voltage readings are not as described, replace sensor.
7. 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.