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

DTC P0117 ENGINE COOLANT TEMPERATURE CIRCUIT LOW

DTC DETECTING CONDITION:

Immediately at fault recognition

TROUBLE SYMPTOM:

• Hard to start

• Erroneous idling

• Poor driving performance

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode and Inspection Mode

WIRING DIAGRAM:

STEPCHECKYESNO

1.CHECK CURRENT DATA.

1) Start the engine.

2) Read the data of engine coolant temperature sensor signal using 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 procedure, refer to the general scan tool operation manual.

Is the temperature 150°C (302°F) or more?

Even if the malfunction indicator light illuminates, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

NOTE:

In this case, temporary poor contact of connector may be the cause.

2.CHECK HARNESS BETWEEN ECM AND ENGINE COOLANT TEMPERATURE SENSOR CONNECTOR.

1) Turn the ignition switch to OFF.

2) Disconnect the connector from ECM and engine coolant temperature sensor.

3) Measure the resistance between ECM and chassis ground.

Connector & terminal

(B137) No. 11 — Chassis ground:

Is the resistance 1 MΩ or more?

Replace the engine coolant temperature sensor.

Repair the ground short circuit of harness between ECM and engine coolant temperature sensor.