Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSSUBARU2012IMPREZA WRX STI F4-2.5L DOHC TURBOREPAIR AND DIAGNOSISENGINE, COOLING AND EXHAUSTCOOLING SYSTEMENGINE - COOLANT TEMPERATURE SENSOR/SWITCHCOOLANT TEMPERATURE SENSOR/SWITCH (FOR COMPUTER)TESTING AND INSPECTION
2012 Subaru Impreza WRX STI F4-2.5L DOHC Turbo
Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection
2012 Subaru Impreza WRX STI F4-2.5L DOHC TurboSECTION Testing and Inspection
Engine Coolant Temperature Sensor
INSPECTION
1. Check that the engine coolant temperature sensor has no deformation, cracks or other damages.
2. Immerse the engine coolant temperature sensor and a thermometer in water.
CAUTION: Take care not to allow water to get into the engine coolant temperature sensor connector. Completely remove any water inside.

3. Raise water temperature gradually, measure the resistance between the engine coolant temperature sensor terminals when the temperature is 20°C (68°F) and 80°C (176°F).
NOTE: Agitate the water for even temperature distribution.

INSPECTION
1. Check that the engine coolant temperature sensor has no deformation, cracks or other damages.
2. Immerse the engine coolant temperature sensor and a thermometer in water.
CAUTION: Take care not to allow water to get into the engine coolant temperature sensor connector. Completely remove any water inside.
3. Raise water temperature gradually, measure the resistance between the engine coolant temperature sensor terminals when the temperature is 20°C (68°F) and 80°C (176°F).
NOTE: Agitate the water for even temperature distribution.
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.