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.
Engine Coolant Temperature Sensor: Notes
A malfunction in Engine Coolant Temperature (ECT) sensor circuit can set a related Diagnostic Trouble Code (DTC). For testing procedure, see appropriate SELF-DIAGNOSTICS article. An out-of-calibration ECT sensor may not set a DTC. Use the following procedure to test sensor calibration.
Disconnect ECT sensor harness connector. Using an ohmmeter, measure resistance of ECT sensor at specified temperatures. See ECT SENSOR RESISTANCE VALUES table. Resistance should be high when engine is cold and drop as engine warms. With vehicle sitting overnight, IAT sensor and ECT sensor should have close to the same resistance reading. If resistance is not within specification, replace ECT sensor.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.