Oxygen Sensor: Testing and Inspection
HEATED OXYGEN SENSOR CHECKRequired Special Tools:
- MB991502: Scan Tool (MUT-II)
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
- MB991658: Test Harness Set
- MD998464: Test Harness
1. Using the scan tool MB991502 or MB991958, 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 [4.5 - 8.0 Ohms at 20 °C (68 °F)] between terminal No. 1 (red clip of special tool) and terminal No. 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 No. 1 (red clip) of the heated oxygen sensor connector to the positive battery terminal and terminal No. 3 (blue clip) to the negative battery terminal.
6. Connect a digital voltage meter between terminal No. 2 (black clip) and terminal No. 4 (white clip).
Standard Value:
2. While repeatedly revving the engine, measure the heated oxygen sensor output voltage.
3. 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 Exhaust Manifold.
1. Using scan tool MB991502 or MB991958, 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 MB991658 to the connector on the heated oxygen sensor side.
2. Make sure that there is continuity [11 - 18 kOhms at 20 °C (68 °F)] between terminal No. 3 and terminal No. 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.
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 No. 3 of the heated oxygen sensor connector to the positive battery terminal and terminal No. 4 to the negative battery terminal.
6. Connect a digital voltage meter between terminal No. 1 and terminal No. 2.
Standard Value:
2. While repeatedly revving the engine, measure the heated oxygen sensor output voltage.
3. If the voltage is not within the standard value, replace the heated oxygen sensor.
NOTE: For removal and installation of the heated oxygen sensor, refer to Exhaust Pipe and Main Muffler.