Oxygen Sensor: Testing and Inspection

SENSOR INSPECTION

Oxygen Sensor Testing:

1. Warm up engine and run at idle.
2. Separate sensor connector.
3. Connect a voltmeter between sensor connector terminal "A" and ground.
4. Increase and decrease engine speed several times. When speed is increased, check that meter reads 0.5V - 1.0V. When speed is decreased, check that meter reads 0 - 0.4V.
5. If not as specified, replace sensor.

SENSITIVITY INSPECTION

NOTE: This test requires use of Mazda Self-Diagnosis Checker (SST #49 H018 9A1) or equivalent aftermarket "Scan" tool. Do not ground test connector (Green: 1 pin) while checking oxygen sensor sensitivity.

1. Warm up engine and run at idle.
2. Connect SST to check connector.
3. Increase engine speed to between 2000 and 3000 rpm. Check that monitor lamp flashes "ON" and "OFF" more than 8 times in 10 seconds.

NOTE: With brake pedal depressed, monitor lamp will show operation of right side oxygen sensor. With brake pedal released, monitor lamp will show operation of left side oxygen sensor.