Oxygen Sensor: Testing and Inspection

Oxygen Sensor Inspection:

1. Warm up engine and run it idle.
2. Disconnect oxygen sensor wiring harness connector.
3. Connect a voltmeter between oxygen sensor connector (oxygen sensor side) and ground.
4. Run engine at 4,500 rpm until voltmeter indicates approx. 0.7 volts.
5. Increase and decrease engine speed suddenly several times. When speed is increased, check that voltmeter reads between 0.5 and 1.0 volts. When speed is decreased, check that voltmeter reads between 0 and 0.4 volts. Reconnect oxygen sensor connector.
6. If not as specified, replace oxygen sensor.

Diagnostic Sensor Connector:

7. Connect self diagnosis tester to check connector and negative battery terminal.

NOTE: Do not ground test connector (Green:1-pin) during this test.

8. Increase the engine speed to between 2,000 and 3,000 rpm and check that monitor lamp flashes for 10 seconds. It should flash eight or more times in the ten second period. Disconnect diagnostic tester.

Oxygen sensor input voltage can be check at ECU terminal 2N.