Oxygen Sensor: Testing and Inspection

Fig. 72 Oxygen sensor connector terminal identification.:

1. Warm up engine and run at idle.
2. Disconnect connector of oxygen sensor wiring harness.
3. Connect voltmeter between oxygen sensor connector terminal A and ground, Fig. 72.
4. Increase and decrease engine speed suddenly several times. When speed is increased, check whether meter reads .5---1 volt and when speed is decreased, check whether meter reads 0---.4 volt.
5. If readings are not as specified, replace oxygen sensor.
6. Inspect sensitivity of oxygen sensor as follows:
a. Warm up engine and run at idle.
b. Connect system checker to check connector. Do not ground green, 1 pin test connector during inspection of oxygen sensor sensitivity.
c. Increase engine speed to 2000---3000 RPM and check that monitor lamp flashes more than 8 times in 10 seconds.
7. Inspect heater as follows:
a. Disconnect connector of oxygen sensor wiring harness.
b. Connect ohmmeter between terminals B and C (oxygen sensor side) and check for continuity.
c. If there is no continuity, replace oxygen sensor.