Oxygen Sensor: Testing and Inspection

Heated oxygen sensors

Inspection of terminal voltage for front & rear heated oxygen sensor
1. Warm up the engine to normal operating temperature.
2. Run engine at idle speed.
3. Connect a voltmeter between terminal 1 (LG/R) and ground.
4. Increase and decrease engine speed quickly several times.
5. Verify that meter reading varies between 0 - 1.0 V.

NOTE: Rear oxygen sensor voltage does not fluctuate as quickly as front oxygen sensor.

6. If not as specified, inspect:
- On-board diagnostic system
- System inspection
- Intake manifold vacuum
- Fuel line pressure

7. If all systems are normal, replace the heated oxygen sensor.

Inspection of front & rear heated oxygen sensor heaters
1. Ensure ignition switch is OFF.
2. Disconnect heated oxygen sensor connector.
3. Connect ohmmeter between terminals 1 and 3 and measure resistance.

Specification: Approx. 3 - 7 Ohms (68 °F {20 °C})

4. If not as specified, replace heated oxygen sensor.

Tightening Torque: 22 - 36 lb-ft (30 - 49 N.m, 3-5 kg-m)




5. Reconnect heated oxygen sensor connector.