Front Oxygen Sensor Test

1. Disconnect the heated oxygen sensor connector.
2. Check that there is continuity between terminal 3 and terminal 4 on the heated oxygen sensor connector.
3. If there is no continuity, replace the heated oxygen sensor.
4. Warm up the engine until engine coolant is 80°C (176°F) or higher.
5. Use the jumper wires to connect terminal 3 of the heated oxygen sensor connector to the battery (+) terminal and terminal 4 to the battery (-) terminal.

CAUTION: Be very careful when connecting the jumper wires, or the heated oxygen sensor can be damaged.

6. Connect a digital voltage meter between terminal 1 and terminal 2.
7. While repeatedly racing the engine, measure the heated oxygen sensor output voltage.
Standard value:
- Engine: When racing the engine
- Heated oxygen sensor output voltage: 0.6-1.0 V
- Remarks: If you make the air/fuel ratio rich by engine repeatedly, a normal heated oxygen sensor will output a voltage of 0.6-1.0 V.

8. If the sensor is defective, replace the heated oxygen sensor.