STEP 1. Check the heated oxygen sensor (rear).
(1) Disconnect the heated oxygen sensor (rear) connector and connect test harness special tool MB991658 to the connector on the heated oxygen sensor (rear) side.
(2) Warm up the engine until engine coolant temperature reaches 80°C (176°F) or higher.
(3) Drive at 50 km/h (31mph) or more for 10 minutes.
(4) Connect a digital voltage meter between terminal O2RL line and terminal ORLE line.
(5) Measure the output voltage of heated oxygen sensor under the following driving.- Transaxle: 2nd
- Drive with wide open throttle
- Engine: 3,500 r/min or more
(6) Standard value: 0.6 - 1.0 V
note | If the temperature of sensing area does not reach the high temperature [of approximately 400°C (752°F) or more] even though the heated oxygen sensor is normal, the output voltage would be possibly low in spite of the rich air-fuel ratio. |
note | When the vehicle is driven with high loads, the temperature of the sensing area of the heated oxygen sensor is sufficiently high. Thus, it is not necessary to apply the voltage to the heater. |
Is the measured voltage between 0.6 and 1.0 volt?
Go to Step 2. Replace the heated oxygen sensor (rear). Then go to Step 6.