Front Oxygen Sensor Test

1. Disconnect the heated oxygen sensor connector and connect the special tool (test harness) to the connector on the heated oxygen sensor side.
2. Make sure that there is continuity [Approx. 12 ohms at 2O°C (68°F)] between terminal 1 (red clip of special tool) and terminal 3 (blue clip of special tool) 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 8O°C (176°F) or higher.





5. Use the jumper wires to connect terminal 1 (red clip) of the heated oxygen sensor connector to the battery (+) terminal and terminal 3 (blue clip) to the battery (-) terminal.

CAUTION: Be very careful when connecting the jumper wires; incorrect connection can damage the heated oxygen sensor.

6. Connect a digital voltage meter between terminal 2 (black clip) and terminal 4 (white clip).
7. While repeatedly racing the engine, measure the heated oxygen sensor output voltage.

Engine Heated oxygen sensor Remarks
output voltage

When 0.6 - 1.0 V If you make the air/fuel ratio
racing rich by racing the engine
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.