FixVault

Check Engine Coolant Temperature Sensor

WARNING: This page is about a different car, the 2005 Subaru Baja. However, it is still accessible from the selected car via links, so may be relevant.
ENGINE COOLANT TEMPERATURE SENSOR

Step Check Yes No
1 CHECK ENGINE COOLANT TEMPERATURE SENSOR. 
Check engine coolant temperature sensor.
BASIC DIAGNOSTIC PROCEDURE . > or < Ref. to BASIC DIAGNOSTIC PROCEDURE . >
Is engine coolant temperature sensor OK? Go to step 2.  Replace engine coolant temperature sensor.
2 CHECK HARNESS BETWEEN ENGINE COOLANT TEMPERATURE SENSOR AND COMBINATION METER. 
  1. Turn ignition switch to OFF.
  2. Disconnect connector from engine coolant temperature sensor and combination meter.
  3. Measure resistance between engine coolant temperature sensor harness connector and combination meter harness connector.

Connector & terminal 
Normal meter: 
(E8) No. 3 - 012) No. 8: 
Is the measured value less than 10 ohm? Go to step 3.  Repair wiring harness.
3 CHECK WATER TEMPERATURE GAUGE GROUND CIRCUIT. 
Measure resistance between combination meter harness connector terminal and chassis ground.
Connector & terminal 
(i12) No. 9 - Chassis ground: 
Is the measured value less than 10 ohm? Check water temperature gauge. < Ref. To , REMOVAL , Water Temperature Gauge. > Repair wiring harness.