Oxygen Sensor: Testing and Inspection
HEATED OXYGEN SENSOR CHECKRequired Special Tools:
- MB991958: Scan tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
- MB991316: Test Harness
- MD998464: Test Harness
[Right bank and left bank heated oxygen sensor (front)]
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 [4.5-8.0 ohms at 20 °C (68 °F)] between terminal No. 1 (red clip) and terminal No. 3 (blue clip) 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. Rev the engine for 5 minutes or more with the engine speed of 4,500 r/min.
6. Connect a digital voltage meter between terminal No. 2 (black clip) and terminal No. 4 (white clip).
7. While repeatedly revving the engine, measure the heated oxygen sensor output voltage.
CAUTION:
- Be very careful when connecting the jumper wire; incorrect connection can damage the oxygen sensor.
- Be careful the heater is broken when voltage of beyond 8V is applied to the oxygen sensor heater.
NOTE: If the sufficiently high temperature (of approximate 400 ° C or more) is not reached although the oxygen sensor is normal, the output voltage would be possibly low although the rich air-fuel ratio. Therefore, if the output voltage is low, use a jumper wire to connect the terminal No. 1 (red clip of special tool) and the terminal No. 3 (blue clip of special tool) of the oxygen sensor with a (+) terminal and (-) terminal of 8 V power supply respectively, then check again.
8. If the output voltage is not within the standard value, replace the heated oxygen sensor.
NOTE: For removal and installation of the heated oxygen sensor, refer to intake and exhaust, Exhaust Pipe and Main Muffler.
[Right bank and left bank heated oxygen sensor (rear)]
1. Disconnect the heated oxygen sensor connector and connect special tool MB991316 to the connector on the heated oxygen sensor side.
2. Make sure that there is continuity [11-18 ohms at 20 °C (68 °F)] between terminal No. 1 (red clip) and terminal No. 3 (blue clip) 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. Drive at 50 km/h (31 mph) or more for 10 minutes.
6. Connect a digital voltage meter between terminal No. 2 (black clip) and terminal No. 4 (white clip).
7. Measure the output voltage of the heated oxygen sensor under the following driving.
- Transaxle: 2nd speed (A/T: "L" range)
- Drive with wide open throttle
- Engine: 3,500 r/min or more
8. If the output voltage is not within the standard value, replace the heated oxygen sensor.
NOTE:
- If the sufficiently high temperature (of approximate 400 °C or more) is not reached although the oxygen sensor is normal, the output voltage would be possibly low although the rich air-fuel ratio.
- For removal and installation of the heated oxygen sensor, refer to intake and exhaust, Exhaust Pipe and Main Muffler.