Upstream Sensor

Heated Oxygen Sensor Check:

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 4 of the heated oxygen sensor connector to the battery (+) terminal and terminal 3 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: When racing engine voltage should be: 0.6-1.0 V
- If you make the air/fuel ratio rich by racing the 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.