Grand AM L4-138 2.3L VIN A MFI (1992)
Oxygen Sensor: Testing and Inspection
VISUAL INSPECTION:
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Connectors and wires
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Housing and insulator for cracks/damage
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Sensor tip for silicone contamination (white powdery coating)
PERFORMANCE TEST: Checks working range and response (speed).
1.
Warm engine
2.
Install DVOM between sensor and ground (2 volt D.C. range)
3.
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).
4.
Drive sensor rich: The use of a properly adjusted propane flowmeter (J-26911) is industry standard.
Voltage should increase to at least 0.8 volts within two to three seconds.
5.
Drive sensor 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.
6.
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.
7.
Reconnect all hoses and electrical connectors. Clear all codes set and retrain idle.
