DTC P0118 Engine Coolant Temperature Circuit High Input

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

DTC DETECTING CONDITION:

Detect as soon as malfunction occurs.
GENERAL DESCRIPTION < Ref. to DTC P0118 ENGINE COOLANT TEMPERATURE CIRCUIT HIGH INPUT , Diagnostic Trouble Code (DTC) Detecting Criteria. >

TROUBLE SYMPTOM:

Hard to start
Erroneous idling
Poor driving performance

CAUTION: After repair or replacement of faulty parts, conduct Clear Memory Mode < Ref. to , OPERATION , Clear Memory Mode.> and Inspection Mode < Ref. to , OPERATION , Inspection Mode.>.

WIRING DIAGRAM:

Fig 1: Wiring Diagram - DTC P0118 Engine Coolant Temperature Circuit High Input

Courtesy of SUBARU OF AMERICA, INC.

DTC P0118 DIAGNOSTIC 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 OBD-II general scan tool. NOTE: Subaru Select Monitor For detailed operation procedure, refer to the "READ CURRENT DATA FOR ENGINE". < Ref. to , SUBARU SELECT MONITOR . > OBD-II general scan tool For detailed operation procedure, refer to the OBD-II general scan tool instruction manual .	Is the engine coolant temperature less than -40°C (-40°F)?	Go to step 2.	Repair poor contact. NOTE: In this case, repair the following: Poor contact in engine coolant temperature sensor Poor contact in ECM Poor contact in coupling connector Poor contact in joint connector
2. CHECK HARNESS BETWEEN ENGINE COOLANT TEMPERATURE SENSOR AND ECM CONNECTOR. Turn the ignition switch to OFF. Disconnect the connector from 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 battery short circuit in 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 OFF. 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 battery short circuit in 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 harness and connector. NOTE: In this case, repair the following: Open circuit in harness between ECM and engine coolant temperature sensor connector Poor contact in engine coolant temperature sensor connector Poor contact in ECM connector Poor contact in coupling connector Poor contact in 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 harness and connector. NOTE: In this case, repair the following: Open circuit in harness between ECM and engine coolant temperature sensor connector Poor contact in engine coolant temperature sensor connector Poor contact in ECM connector Poor contact in coupling connector Poor contact in joint connector