)
- Disconnect the oxygen sensor connector and connect the special tool Test harness (MB991658) to the connector on the oxygen sensor side.
- Make sure that there is continuity (4.5 -
8.0 Ω
at
20°C ) between terminal No. 1 and No. 3 on the oxygen sensor connector.
- If there is no continuity, replace the oxygen sensor.
- Warm up the engine until engine coolant is
80°C or higher.
)
- Perform a tracing for 5 minutes or more with the engine speed of 4,500 r/min.
- Connect a digital voltage meter between terminal No. 3 and No. 4.
- While repeatedly racing the engine, measure the oxygen sensor output voltage.
| Engine |
Oxygen sensor output voltage |
Remarks |
|---|---|---|
| When racing the engine |
0.6 -
1.0 V |
If you make the air/fuel ratio rich by racing the engine repeatedly,
a normal oxygen sensor will output a voltage of 0.6 -
1.0 V. |
- 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.
CAUTIONNOTE: 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.2
(to be the red clip of special tool) and the terminal No. 1 (to be the blue clip of special
tool) of the (front) oxygen sensor with a (+) terminal and (-) terminal of 8 V power
supply respectively, then check again.
- If the sensor is defective, replace the oxygen sensor.
NOTE: For removal and installation of the oxygen sensor, refer to GROUP 15 -
Exhaust
Pipe and Main Muffler 
.
.)
- Disconnect the oxygen sensor connector and connect the special tool Test harness (MB991658) to the connector on the oxygen sensor side.
)
- Make sure that there is continuity (11 -
18 Ω
at
20°C ) between terminal No. 3 and No. 4 on the oxygen sensor connector.
- If there is no continuity, replace the oxygen sensor.
- Warm up the engine until engine coolant is
80°C or higher.
- Perform a tracing for 5 minutes or more with the engine speed of 4,500 r/min.
- Connect a digital voltage meter between terminal No. 1 and No. 2.
- While repeatedly racing the engine, measure the oxygen sensor output voltage.
| Engine |
Oxygen sensor output voltage |
Remarks |
|---|---|---|
| When racing the engine |
0.6 -
1.0 V |
If you make the air/fuel ratio rich by racing the engine repeatedly,
a normal oxygen sensor will output a voltage of 0.6 -
1.0 V. |
- 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.
CAUTIONNOTE: 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.3
(to be the red clip of special tool) and the terminal No. 4 (to be the blue clip of special
tool) of the (rear) oxygen sensor with a (+) terminal and (-) terminal of 8 V power
supply respectively, then check again.
- If the sensor is defective, replace the oxygen sensor.
NOTE: For removal and installation of the oxygen sensor, refer to GROUP 15 -
Exhaust
Pipe and Main Muffler .
.