Oxygen Sensor: Testing and Inspection

Heated oxygen sensor (front)

HO2S (Upstream):

1. Disconnect the heated oxygen sensor connector.

HO2S Check:

2. Check that there is continuity between terminal 1 and terminal 3 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 1 to the battery (-) terminal.

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

HO2S Check:

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

HO2S Value:

Standard value:

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

HO2S Check:

Heated oxygen sensor (rear)
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.

NOTE:
1. If the scan tool does not display the standard value although no malfunction is found by the above-mentioned continuity test and harness check, replace the heated oxygen sensor (rear).