A/T

DTC P0141 - REAR OXYGEN SENSOR HEATER CIRCUIT MALFUNCTION

DTC DETECTING CONDITION:
- Two consecutive driving cycles with fault

CAUTION: After repair or replacement of faulty parts, conduct CLEAR MEMORY MODE and INSPECTION MODE. Refer to How To Clear Diagnostic Trouble Codes.

Wiring Diagram:

WIRING DIAGRAM

11R1: CHECK GROUND CIRCUIT OF ECM.

1. Turn ignition switch to OFF.
2. Disconnect connector from ECM.

Connector & Terminal - [(B134) No.35 - Chassis Ground]:

3. Measure resistance of harness between ECM connector and chassis ground.

CHECK: Is the resistance less than 5 Ohms?

YES: Go to step 11R3.

NO: Go to step 11R2.

11R2: CHECK GROUND CIRCUIT OF ECM.

1. Repair harness and connector.

NOTE: In this case, repair the following:
- Open circuit in harness between ECM and engine ground terminal
- Poor contact in ECM connector
- Poor contact in coupling connector (B22)

Connector & Terminal - [(B134) No.34 - Chassis Ground]:

2. Measure resistance of harness between ECM connector and chassis ground.

CHECK: Is the resistance less than 5 Ohms?

YES: Go to step 11R3.

NO: Repair harness and connector.

NOTE: In this case, repair the following:
- Open circuit in harness between ECM and engine ground terminal
- Poor contact in ECM connector
- Poor contact in coupling connector (B22)

11R3: CHECK CURRENT DATA.

1. Start engine.
2. Read data of rear oxygen sensor heater current using Subaru Select Monitor or OBD-II general scan tool

NOTE:
- Subaru Select Monitor For detailed operation procedure, refer to the "READ CURRENT DATA SHOWN ON DISPLAY FOR ENGINE". Refer to Normal Scan Data Values.
- OBD-II scan tool.
For detailed operation procedures, refer to the OBD-II General Scan Tool Instruction Manual.

CHECK: Is the value more than 0.2 A?

YES: Repair connector.

NOTE: In this case, repair the following:
- Poor contact in rear oxygen sensor connector
- Poor contact in rear oxygen sensor connecting harness connector
- Poor contact in ECM connector

NO: Go to step 11R4.

111R4:CHECK OUTPUT SIGNAL FROM ECM.

1. Start and idle the engine.

Connector & Terminal - [(B134) No.21 (+) - Chassis Ground (-)]:

2. Measure voltage between ECM connector and chassis ground.

CHECK: Is the voltage less than 1.0 V?

YES: Go to step 11R7.

NO: Go to step 11R5.

11R5:CHECK OUTPUT SIGNAL FROM ECM

Connector & Terminal - [(B134) No.21 (+) - Chassis Ground (-)]:

Measure voltage between ECM connector and chassis ground.

CHECK: Does the voltage change less than 1.0 V by shaking harness and connector of ECM while monitoring the value with voltage meter?

YES: Repair poor contact in ECM connector.

NO: Go to step 11R6.

11R6: CHECK OUTPUT SIGNAL FROM ECM.

1. Disconnect connector from rear oxygen sensor.

Connector & Terminal - [(B134) No.21 (+) - Chassis Ground (-)]:

2. Measure voltage between ECM connector and chassis ground.

CHECK: Is the voltage less than 1.0 V?

YES: Replace ECM.

NO: Repair battery short circuit in harness between ECM and rear oxygen sensor connector. After repair, replace ECM.

11R7: CHECK POWER SUPPLY TO REAR

1. Turn ignition switch to OFF.
2. Disconnect connector from rear oxygen sensor.
3. Turn ignition switch to ON.

Connector & Terminal - [(T6) No.2 (+) - Chassis Ground (-)]:

4. Measure voltage between rear oxygen sensor connector and engine ground or chassis ground.

CHECK: Is the voltage more than 10 V?

YES: Go to step 11R8.

NO: Repair power supply line.

NOTE: In this case, repair the following:
- Open circuit in harness between main relay and rear oxygen sensor connector
- Poor contact in rear oxygen sensor connector
- Poor contact in coupling connector (T5)

11R8: CHECK REAR OXYGEN SENSOR.

1. Turn ignition switch to OFF.

Terminals [No.1 - No.2]:

2. Measure resistance between rear oxygen sensor connector terminals.

CHECK: Is the resistance less than 30 Ohms?

YES: Repair harness and connector.

NOTE: In this case, repair the following:
- Open circuit in harness between rear oxygen sensor and ECM connector
- Poor contact in rear oxygen sensor connector
- Poor contact in ECM connector
- Poor contact in coupling connector (T5)

NO: Replace rear oxygen sensor.