Heated Oxygen Sensor Testing

INSPECTION
Sensor
- Warm up the engine to normal operating temperature.
- Connect the SSTs (Engine Signal Monitor) to the PCM.
- Measure the PCM terminal 3C and 3D voltages.




- If not as specified, inspect the following.
- Harness and connector between heated oxygen sensor and PCM.
- On-board diagnostic system
- System inspection
Intake manifold vacuum
Fuel line pressure
- If all the systems are OK, replace the heated oxygen sensor.




Using the NGS
- Connect the SSTs (NGS) to the data link connector-2.
Select the PID/DATA MONITOR AND RECORD function.
Select "FHO2S", "RHO2S" on the NGS display. The NGS measures and shows the voltage.




It not as specified, inspect the following.
- Harness and connector between heated oxygen sensor and PCM.
- On-board diagnostic system
- System inspection
Intake manifold vacuum
Fuel line pressure
- If all the systems are OK, replace the heated oxygen sensor.

Heater
- Disconnect the heated oxygen sensor connector.
- Measure the resistance between heated oxygen sensor terminals B and C (Front) or D and C (Rear) by using an ohmmeter.

Specification: Approx. 6 ohms @ 20°C (68°F)

- If not as specified, replace the heated oxygen sensor.