1 CHECK REAR OXYGEN SENSOR DATA.
- Warm up the engine until engine coolant temperature is higher than 75°C (167°F), and keep the engine speed at 3, 00 rpm. (2 minutes maximum)
- Read the value of «Front O2 Sensor #2» using the Subaru Select Monitor or a general scan tool.
NOTE:
- Subaru Select Monitor
For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Refer to
SUBARU SELECT MONITOR . >
- General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
|
Is the value of «Front O2 Sensor #2» 0.490 V or more? |
Go to step 6
. |
Go to step 2
. |
2 CHECK REAR OXYGEN SENSOR DATA.
- Warm up the engine until engine coolant temperature is higher than 75°C (167°F), and rapidly reduce the engine speed from 3, 00 rpm.
- Read the value of «Front O2 Sensor #2» using the Subaru Select Monitor or a general scan tool.
NOTE:
- Subaru Select Monitor
For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Refer to
SUBARU SELECT MONITOR . >
- General scan tool
For detailed operation procedures, refer to the
general scan tool operation manual.
|
Is the value of «Front O2 Sensor #2» 0.250 V or less? |
Go to step 6
. |
Go to step 3
. |
| 3 CHECK REAR OXYGEN SENSOR CONNECTOR AND COUPLING CONNECTOR. |
Has water entered the connector? |
Completely remove any water inside. |
Go to step 4
. |
4 CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR CONNECTOR.
- Turn the ignition switch to OFF.
- Disconnect the connector from ECM and rear oxygen sensor.
- Measure the resistance of harness between ECM and rear oxygen sensor connector.
Connector & terminal
(B135) No. 28 - (E25) No. 3:
(B135) No. 30 - (E25) No. 4:
|
Is the resistance less than 1 Ω? |
Go to step 5
. |
Repair the harness and connector.
NOTE:
In this case, repair the following item:
- Open circuit in harness between ECM and rear oxygen sensor connector
- Poor contact of coupling connector
|
5 CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR CONNECTOR.
- Connect the connector to ECM.
- Turn the ignition switch to ON.
- Measure the voltage between rear oxygen sensor connector and chassis ground.
Connector & terminal
(E25) No. 3 (+) - Chassis ground (-):
|
Is the voltage 0.2 - 0.5 V? |
Replace the rear oxygen sensor. Refer to
REAR OXYGEN SENSOR
. > |
Repair the harness and connector.
NOTE:
In this case, repair the following item:
- Open circuit in harness between ECM and rear oxygen sensor connector
- Poor contact of ECM connector
- Poor contact of coupling connector
|
6 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
NOTE:
Check the following items.
- Looseness and improper fitting of exhaust system parts
- Damage (crack, hole etc.) of parts
- Loose part and improper installation between front oxygen (A/F) sensor and rear oxygen sensor
|
Is there any fault in exhaust system? |
Repair or replace faulty parts. |
Replace the rear oxygen sensor. Refer to
REAR OXYGEN SENSOR
. > |