Oxygen Sensor: Testing and Inspection
SENSOR CHECKOxygen Sensor Inspection:
1. Warm up engine and run at idle.
2. Disconnect oxygen sensor wiring harness connector.
3. Connect a voltmeter between oxygen sensor connector "A" (oxygen sensor side) and ground.
4. 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.
5. If not as specified, replace oxygen sensor.
6. Connect self diagnosis tester to check connector.
NOTE: Do not ground test connector (Green:1-pin) during this test.
7. Increase 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 diagnosis tester.
Oxygen sensor input can be checked at ECU terminal 2D.
HEATER
Oxygen Sensor Heater And Terminal ID:
1. Disconnect oxygen sensor harness connector.
2. Connect an ohmmeter between "B" and "C" terminals (oxygen sensor side) and check for continuity.
3. If there is no continuity, replace oxygen sensor.
Oxygen sensor heater output voltage can be measured at ECU terminal 3H. Above 2250 rpm, terminal voltage should be approximately 12V. Below that engine speed, voltage should be below 2.5V.