Oxygen Sensor: Testing and Inspection

OUTPUT VOLTAGE

Output Voltage Check:

1. Warm engine to operating temperature and run at idle.
2. Disconnect oxygen sensor connector. Connect voltmeter between sensor and ground.
3. Run engine at 4500 rpm until meter indicates approximately 0.7V.
4. Increase and decrease engine speed suddenly several times. Verify that meter reads 0.5 - 1.0V when speed is increased and 0 - 0.4V when speed is decreased.
5. If not as specified, replace sensor.

SENSITIVITY

Sensitivity Check:

NOTE: This test requires use of Mazda Self-Diagnosis Checker (SST #49 H018 9A1) or suitable aftermarket "Scan" tool.

1. Warm engine to operating temperature.
2. Connect test tool to check connector.
3. Increase engine speed to between 2000 and 3000 rpm. Verify that monitor lamp flashes more than 8 times during a 10 second period.
4. If not as specified, replace sensor.