Heated Oxygen Sensor Check

Required Special Tool:
MD998464: Test Harness


1. Using the scan tool, observe HO2S reading. If values are unsatisfactory or if Scan tool is not available, use the following procedure:

(1) Disconnect the heated oxygen sensor connector and connect special tool MD998464 to the connector on the heated oxygen sensor side.




(2) Make sure that there is continuity [7-40 ohms at 20°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 80°C (176°F) or higher.

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




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




Standard Value

NOTE: For removal and installation of the heated oxygen sensor; refer to Exhaust Pipe and Main Muffler.

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


1. Disconnect the heated oxygen sensor connector and connect special tool, MD998464, to the connector on the heated oxygen sensor side.




2. Make sure that there is continuity [7-40 ohms at 20°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.

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

NOTE: For removal and installation of the oxygen sensor; refer to Exhaust Pipe and Main Muffler.

3. If there is no continuity, replace the heated oxygen sensor.