DTC P0117 Engine Coolant Temperature Sensor 1 Circuit Low: Notes

DTC DETECTING CONDITION:

Immediately at fault recognition

TROUBLE SYMPTOM:

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to OPERATION , Clear Memory Mode.>, and Inspection Mode <Ref. to PROCEDURE , Inspection Mode.>.
Use the check board when measuring the ECM terminal voltage and resistance.

WIRING DIAGRAM:

Engine Electrical System <Ref. to WIRING DIAGRAM , Engine Electrical System.>

Fig 1: Engine Coolant Temperature Sensor 1 - Wiring Diagram (Low)

Courtesy of SUBARU OF AMERICA, INC.

Step	Check	Yes	No
1 CHECK CURRENT DATA. Start the engine. Read the value of «Coolant Temp.» using the Subaru Select Monitor or a general scan tool. NOTE: Subaru Select Monitor For detailed operation procedures, refer to "Current Data Display For Engine". <Ref. to Subaru Select Monitor .> General scan tool For detailed operation procedures, refer to the general scan tool operation manual.	Is the value of «Coolant Temp.» 150°C (302°F) or more?	Go to step 2 .	Even if DTC is detected, 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, temporary open or short circuit of harness may be the cause.
2 CHECK HARNESS BETWEEN ECM AND ENGINE COOLANT TEMPERATURE SENSOR CONNECTOR. Turn the ignition switch to OFF. Disconnect the connector from ECM. Disconnect the connectors from the engine coolant temperature sensor. Measure the resistance between the ECM connector and engine ground. Connector & terminal (E158) No. 38 - Engine ground:	Is the resistance 1 MΩ or more?	Replace the engine coolant temperature sensor. <Ref. to Engine Coolant Temperature Sensor .>	Repair the short circuit to ground in harness between ECM connector and engine coolant temperature sensor connector.

Step

Check

Yes

1 CHECK CURRENT DATA.

Start the engine.
Read the value of «Coolant Temp.» using the Subaru Select Monitor or a general scan tool.

NOTE:

For detailed operation procedures, refer to "Current Data Display For Engine". <Ref. to Subaru Select Monitor .>

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

Is the value of «Coolant Temp.» 150°C (302°F) or more?

Go to step 2 .

Even if DTC is detected, 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, temporary open or short circuit of harness may be the cause.

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

Turn the ignition switch to OFF.
Disconnect the connector from ECM.
Disconnect the connectors from the engine coolant temperature sensor.
Measure the resistance between the ECM connector and engine ground.
Connector & terminal

(E158) No. 38 - Engine ground:

Is the resistance 1 MΩ or more?

Replace the engine coolant temperature sensor. <Ref. to Engine Coolant Temperature Sensor .>

Repair the short circuit to ground in harness between ECM connector and engine coolant temperature sensor connector.