Oxygen Sensor: Testing and Inspection

VISUAL INSPECTION:

- Connectors and wires
- Housing and insulator for cracks/damage
- Sensor tip for silicone contamination (white powdery coating)

PERFORMANCE TEST: Checks working range and response (speed).

- Warm engine
- Install DVOM between sensor and ground (2 volt D.C. range)
- "RUN" engine at steady cruise speed (about 2500 rpm)
Voltage should vary at least eight times in ten seconds between 0.2 and 0.8 volts (normal range).
- Drive system rich: The use of a properly adjusted propane flow-meter (J-26911) is industry standard.
Voltage should increase to at least 0.8 volts within two to three seconds.
- Drive system lean: Create a vacuum leak from a source that is not an ECM input or output.
Voltage should drop to at least 0.3 volts within two to three seconds.
NOTE: After each test the O2 sensor should return to normal operating range within two to three seconds.
- O2 Sensor should be replaced for failure to pass any of the tests above.
NOTE: A CEC system that is operating excessively rich or lean will drive the 02 sensor to its maximum range and should be repaired first and not diagnosed as a 02 sensor failure.
- Reconnect all hoses and electrical connectors. Clear all codes set and retrain idle.