ENGINE (DIAGNOSTICS)(H4DO) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)

DTC P0103 MASS OR VOLUME AIR FLOW CIRCUIT HIGH INPUT

DTC DETECTING CONDITION:

Immediately at fault recognition

TROUBLE SYMPTOM:

• Improper idling

• Engine stalls.

• Poor driving performance

CAUTION:

After repairing or replacing the defective part, perform the Clear Memory Mode and Inspection Mode .

WIRING DIAGRAM:

STEPCHECKYESNO

1.CHECK CURRENT DATA.

1) Start the engine.

2) Read the data of air flow sensor signal using the Subaru Select Monitor or general scan tool.

NOTE:

• Subaru Select Monitor

For detailed operation procedures, refer to “READ CURRENT DATA FOR ENGINE”.

• General scan tool

For detailed operation procedures, refer to the general scan tool operation manual.

Is the voltage 5 V or more?

Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the fault condition, and reperform the check.

NOTE:

In this case, there may be a temporary connector contact failure.

2.CHECK HARNESS BETWEEN ECM AND MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR CONNECTORS.

1) Turn the ignition switch to OFF.

2) Disconnect the connector from the mass air flow and intake air temperature sensor.

3) Start the engine.

4) Read the data of air flow sensor signal using the Subaru Select Monitor or general scan tool.

NOTE:

• Subaru Select Monitor

For detailed operation procedures, refer to “READ CURRENT DATA FOR ENGINE”.

• General scan tool

For detailed operation procedures, refer to the general scan tool operation manual.

Is the voltage 5 V or more?

Repair the short circuit to power in the harness between the ECM and the mass air flow and intake air temperature sensor connectors.

3.CHECK HARNESS BETWEEN ECM AND MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR CONNECTORS.

1) Turn the ignition switch to OFF.

2) Measure the resistance of harness between the mass air flow and intake air temperature sensor connector and engine ground.

Connector & terminal

(B3) No. 2 — Engine ground:

Is the resistance less than 5 Ω?

Repair the harness and connector.

NOTE:

In this case, repair the following item:

• Open circuit of harness between ECM and mass air flow and intake air temperature sensor connectors.

• Poor contact in ECM connector

4.CHECK FOR POOR CONTACT.

Check for any poor contact between the mass air flow and intake air temperature sensor connectors.

Is there poor contact in the mass air flow and intake air temperature sensor connectors?

Repair any poor contact of the mass air flow and intake air temperature sensor connectors.

Replace the mass air flow and intake air temperature sensor.