Oxygen Sensor: Testing and Inspection

Oxygen Sensor Testing:

TERMINAL VOLTAGE

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 3000 rpm until meter indicates approximately 0.55V.
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

NOTE: This test requires use of Mazda System Selector (SST #49 B019 9A0) and Self-Diagnosis Checker (SST #49 H018 9A1) or suitable aftermarket equipment.

1. Warm engine to operating temperature.
2. Connect test tools to diagnosis connector.
3. Set switch "A" to position 1.
4. Set test switch to "O2 Monitor."
5. Increase engine speed to between 2000 and 3000 rpm. Verify that monitor lamp flashes more than 8 times during a 10 second period. If not as specified, replace sensor.
6. Turn ignition switch "OFF."
7. Disconnect negative battery terminal and depress brake pedal for at least 5 seconds to erase ECU malfunction code memory created during testing.