DTC P0118 Engine Coolant Temperature Circuit High

WARNING: This page is about a different variant/trim than selected.

DTC DETECTING CONDITION:

Immediately at fault recognition
GENERAL DESCRIPTION < Ref. to DTC P0118 ENGINE COOLANT TEMPERATURE CIRCUIT HIGH , Diagnostic Trouble Code (DTC) Detecting Criteria. >

TROUBLE SYMPTOM:

Hard to start
Erroneous idling
Poor driving performance

CAUTION: After repairing or replacing the defective part, perform the Clear Memory Mode < Ref. to OPERATION , Clear Memory Mode. > and Inspection Mode < Ref. to PROCEDURE , Inspection Mode. >.

WIRING DIAGRAM:

Fig 1: Engine Coolant Temperature Circuit High - Wiring Diagram

DIAGNOSIS PROCEDURE

Step	Check	Yes	No
1 CHECK CURRENT DATA. Start the engine. Read the data of engine coolant temperature sensor signal using Subaru Select Monitor or general scan tool. NOTE: Subaru Select Monitor For detailed operation procedure, refer to "READ CURRENT DATA FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . > General scan tool For detailed operation procedure, refer to the general scan tool operation manual.	Is the engine coolant temperature less than -40°C (-40°F) ?	Go to step 2.	Repair the poor contact. NOTE: In this case, repair the following item: Poor contact of engine coolant temperature sensor Poor contact in ECM Poor contact of coupling connector Poor contact of joint connector
2 CHECK HARNESS BETWEEN ENGINE COOLANT TEMPERATURE SENSOR AND ECM CONNECTOR. Turn the ignition switch to OFF. Disconnect the connectors from the engine coolant temperature sensor. Measure the voltage between engine coolant temperature sensor connector and engine ground. Connector & terminal (E8) No. 2 (+) - Engine ground (-):	Is the voltage more than 10 V?	Repair the battery short circuit of harness between ECM and engine coolant temperature sensor connector.	Go to step 3.
3 CHECK HARNESS BETWEEN ENGINE COOLANT TEMPERATURE SENSOR AND ECM CONNECTOR. Turn the ignition switch to ON. Measure the voltage between engine coolant temperature sensor connector and engine ground. Connector & terminal (E8) No. 2 (+) - Engine ground (-):	Is the voltage more than 10 V?	Repair the battery short circuit of harness between ECM and engine coolant temperature sensor connector.	Go to step 4.
4 CHECK HARNESS BETWEEN ENGINE COOLANT TEMPERATURE SENSOR AND ECM CONNECTOR. Measure the voltage between engine coolant temperature sensor connector and engine ground. Connector & terminal (E8) No. 2 (+) - Engine ground (-):	Is the voltage more than 4 V?	Go to step 5.	Repair the harness and connector. NOTE: In this case, repair the following item: Open circuit of harness between ECM and engine coolant temperature sensor connector Poor contact of engine coolant temperature sensor connector Poor contact in ECM connector Poor contact of coupling connector Poor contact of joint connector
5 CHECK HARNESS BETWEEN ENGINE COOLANT TEMPERATURE SENSOR AND ECM CONNECTOR. Turn the ignition switch to OFF. Measure the resistance of harness between engine coolant temperature sensor connector and engine ground. Connector & terminal (E8) No. 1 - Engine ground:	Is the resistance less than 5 Ω?	Replace the engine coolant temperature sensor. < Ref. to ENGINE COOLANT TEMPERATURE SENSOR . >	Repair the harness and connector. NOTE: In this case, repair the following item: Open circuit of harness between ECM and engine coolant temperature sensor connector Poor contact of engine coolant temperature sensor connector Poor contact in ECM connector Poor contact of coupling connector Poor contact of joint connector