P0141

DTC P0141
REAR OXYGEN SENSOR HEATER CIRCUIT MALFUNCTION (RO2H)

Description
- In order to monitor purifying efficiency of the catalyst the rear oxygen sensor sends a signal to the Engine Control Module (ECM).
- Refer to DTC P0130 front oxygen sensor circuit malfunction.

DTC Detecting Condition
Two consecutive trips with fault











1. Connect Subaru Select Monitor or the OBD-II General Scan Tool and read data.





a. Turn Ignition switch to "OFF".
b. Connect Subaru Select Monitor or the OBD-II General Scan Tool to Data Link Connector.
c. Turn Ignition switch to "ON" and Subaru Select Monitor or OBD-II General Scan Tool switch to "ON".
d. Start Engine.
e. Read data on Subaru Select Monitor or OBD-II General Scan Tool.

Subaru Select Monitor
- Designate mode using function key.
- Function mode: F30.

[CHECK]: Is the reading of F30 0.2 A, or more?
[NO]: Go to step 2.
[YES]: Repair connector.

NOTE: In this case poor contact of rear Oxygen Sensor connector and Engine Control Module (ECM) connector can be the possible cause.

OBD-II Scan Tool
- For detailed operation procedures refer to the OBD-II General Scan Tool Instruction Manual.

2. Check output signal from ECM. (Using voltage meter.)





a. Start and idle the engine.
b. Measure voltage between ECM and body.
[CHECK]: Connector & terminal:
(B84) No. 43 - Body/1.0 Volt, or less.
[YES]: Go to step 3.
[NO]: Go to next [CHECK].

[CHECK]: Is the voltage less than 1.0 Volt while shaking harness and connector of ECM?
[YES]: Repair poor contact in ECM connector.
[NO]: Go to next step.





c. Disconnect connector from rear oxygen sensor.
d. Measure voltage between ECM and body.
[CHECK]: Connector & terminal:
(B84) No. 43 - Body/1.0 Volt, or less.
[YES]: Replace ECM.
[NO]: Repair short circuit of harness between ECM and rear oxygen sensor connector. After repair short circuit of harness replace ECM.

3. Check power supply to rear oxygen sensor circuit.





a. Turn Ignition switch to "OFF".
b. Disconnect connector from rear oxygen sensor.
c. Turn Ignition switch to "ON".
d. Measure voltage between rear oxygen sensor connector and body.
[CHECK]: Connector & terminal:
(T6) No. 2 - Body/10 Volts, or more.
[YES]: Go to step 4.
[NO]: Repair power supply line.

NOTE: In this case repair poor contact in connector or open circuit of harness between main relay and rear oxygen sensor.

4. Check rear oxygen sensor.





a. Turn Ignition switch to "OFF".
b. Measure resistance between rear oxygen sensor connector terminals.
[CHECK]: Terminals:
No. 1 - No. 2/30 Ohms or less.
[YES]: Repair harness and connector.

NOTE: In this case repair the following.
- Open circuit of harness between rear oxygen sensor connector and ECM connector.
- Poor contact in rear oxygen sensor connector.
- Poor contact in ECM connector.
- Poor contact in rear oxygen sensor connecting harness connector

[NO]: Replace rear oxygen sensor.