Oxygen Sensor: Testing and Inspection

Fig. 49 Oxygen Sensor Connector Plug:

Test the oxygen sensor as follows:

1. Run engine to operating temperature. Engine idle speed must be adjusted correctly.
2. Disconnect oxygen sensor at connector.
3. Connect a voltmeter between ground and pin connector #1 (Fig. 49.) of oxygen sensor plug (on sensor side). Voltmeter should reed 0.1 - 1.0 Volts.
4. If reading is different, replace and retest with new oxygen sensor.
5. Disconnect voltmeter.
6. Connect an ohm meter between pin connector #2 and #3 (Fig. 49.). Ohm meter should display some resistance. If ohm meter measures no or infinite resistance, heating element is faulty. Replace and retest with new oxygen sensor.
7. Turn engine off.
8. Disconnect the ohm meter and reconnect the oxygen sensor connector.
9. For more complete oxygen sensor system testing refer to Computers and Control Systems.