| 1 CHECK ANY OTHER DTC ON DISPLAY. |
Is any other DTC displayed? |
Check DTC using "List of Diagnostic Trouble Code (DTC)". <Ref. to
LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . >
NOTE:
In this case, it is not necessary to inspect DTC P0140.
|
Go to step 2. |
2 CHECK REAR OXYGEN SENSOR DATA.
- Warm-up the engine until engine coolant temperature is above 70°C (158°F), and keep the engine speed at 3,000 rpm. (Max. 2 minutes)
- Read the data of rear oxygen sensor signal using Subaru Select Monitor or general scan tool.
NOTE:
- For MT vehicles, depress the clutch pedal.
- Subaru Select Monitor
For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". <Ref. to
SUBARU SELECT MONITOR . >
- General scan tool
For detailed operation procedures, refer to the General Scan Tool Instruction Manual.
|
Is the voltage 490 mV or more? |
Go to step 7. |
Go to step 3. |
3 CHECK REAR OXYGEN SENSOR DATA.
- Warm-up the engine until engine coolant temperature is above 70°C (158°F), and rapidly reduce the engine speed from 3,000 rpm.
- Read the data of rear oxygen sensor signal using Subaru Select Monitor or general scan tool.
NOTE:
- For MT vehicles, depress the clutch pedal.
- Subaru Select Monitor
For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". <Ref. to
SUBARU SELECT MONITOR . >
- General scan tool
For detailed operation procedures, refer to the General Scan Tool Instruction Manual.
|
Is the voltage 250 mV or less? |
Go to step 7. |
Go to step 4. |
| 4 CHECK REAR OXYGEN SENSOR CONNECTOR AND COUPLING CONNECTOR. |
Does water enter the connector? |
Dry the water thoroughly. |
Go to step 5. |
5 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. 4 - (B18) No. 3:
(B135) No. 30 - (B18) No. 4:
|
Is the resistance 3 Ω or more? |
Repair the open circuit of harness between ECM and rear oxygen sensor connector. |
Go to step 6. |
6 CHECK HARNESS BETWEEN REAR OXYGEN SENSOR AND ECM CONNECTOR.
- Turn the ignition switch to OFF.
- Disconnect the connector from the rear oxygen sensor.
- Turn the ignition switch to ON.
- Measure the voltage between rear oxygen sensor harness connector and chassis ground.
Connector & terminal
(B18) No. 3 (+) - Chassis ground (-):
|
Is the voltage 0.2 - 0.5 V? |
Replace the rear oxygen sensor. <Ref. to
REAR OXYGEN SENSOR
. > |
Repair the harness and connector.
NOTE:
In this case, repair the following item:
- Open circuit in harness between rear oxygen sensor and ECM connector
- Poor contact in rear oxygen sensor connector
- Poor contact in ECM connector
|
7 CHECK EXHAUST SYSTEM.
Check exhaust system parts.
NOTE:
Check the following items.
- Looseness and improper attachment of exhaust system parts
- Damage (crack, hole etc.) of parts
- Looseness and improper attachment of parts 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. <Ref. to
REAR OXYGEN SENSOR
. > |