Main Oxygen Sensor

Fig. 41 Oxygen Sensor Test Connections:

1. Start engine and warm-up to normal operating temperature.
2. Connect the positive (+) probe of a voltmeter to terminal VF1 of the engine check connector, and the negative (-) probe to terminal E1. Fig. 41
3. Run engine at 2,500 rpm for 90 seconds to preheat oxygen sensor.

Fig. 41a Check Connector And Service Wire:

4. Using a service wire, connect terminals TE1 and E1 of the check connector, Fig. 41a, while maintaining engine speed at 2,500 rpm.
5. Observe the number of times the voltmeter oscillates in 10 seconds.
6. If 8 or more oscillations occur, the oxygen sensor is operating normally. If less than 8 oscillations occur, proceed with testing procedure.
7. Disconnect terminals TE1 and E1 and maintain engine speed at 2,500 rpm.
8. Measure voltage between terminals VF1 and E1. If voltmeter reads 0 volts, extract diagnostic codes and follow appropriate testing procedures.
9. If voltmeter reads more than 0 volts, replace the main oxygen sensor.
10. After replacement, repeat steps 3 - 6 and note oscillations. If zero oscillations occur with new oxygen sensor, replace ECU.