HO2S Inspection Procedures

SENSOR INSPECTION
- Warm up the engine to normal operating temperature.




- Connect the SSTs (Engine Signal Monitor) to the ECM.




- Measure the ECM terminal 3C and 3D voltages.
- If not as specified, inspect the following:
- Harness and connector between heated oxygen sensor and ECM.
- On-board diagnostic system
- 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 of the NGS.
- Select "FHO2S", "RHO2S" on the NGS display. The NGS measures and shows the voltage.




- If not as specified, inspect the following:
- Harness and connector between heated oxygen sensor and ECM.
- On-board diagnostic system
- 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 D and C by using an ohmmeter.

Specification: Approx. 13 ohms @ 20°C (68°F)

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