Oxygen (02) Sensor Test

Note:
The best way to resolve a Code 45 or driveability incident is to carefully go through ALL the steps contained within this bulletin.











With consult plugged in and turned on check the operation of the O2 sensor with the engine at operating temperature and just above 2000 rpm





The O2 sensor voltage should fluctuate between 0.0 and 1.0 Volts when graphed as shown. There should be at least 5 peaks upward and 5 peaks downward. The peaks should look similar above 0.5 volts and below 0.5 Volts. A rich mixture will cause the voltage to stay closer to 1.0 Volts, and the graph will have fewer voltage fluctuations.





EXAMPLE: Rich mixture O2 sensor CONSULT printout





EXAMPLE: NG O2 sensor CONSULT printout

1. If the O2 sensor voltage appears NG then check the harness:

2. Turn the ignition switch "OFF".

3. Disconnect the ECM harness connector and O2 sensor harness connector or heated O2 sensor harness connector.

4. Check the harness continuity between the ECM O2 sensor signal terminal and the O2 sensor signal wire terminal at the harness connector itself. There should be no resistance.

5. If there is resistance in the wire, inspect the harness to determine the cause.

6. Check the O2 sensor signal wire for any continuity to ground, there should be no continuity (infinite ohms).

7. If there is continuity to ground, inspect the harness to determine the cause.

8. If the harness checks OK, but the consult reading is NG, check the ECM and harness connectors carefully for any damage or corrosion. If all harness checks are OK, then replace the O2 sensor.