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 (ECT) Sensor
If an ECT sensor-related code is present, perform appropriate DTC test. See TESTS W/CODES - 4.3L article. An out-of-calibration sensor may not set a trouble code. Use following procedure to test sensor calibration. Disconnect ECT sensor harness connector. Measure resistance between ECT sensor terminals. Sensor resistance should be as specified. 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 coolant sensor should have close to the same resistance reading.
| Temperature °F (°C) | Ohms |
|---|---|
| 212 (100) | 177 |
| 158 (70) | 467 |
| 104 (40) | 1459 |
| 68 (20) | 3520 |
| 32 (0) | 9420 |
| 5 (-15) | 21,450 |
| -40 (-40) | 100,700 |
NO RELATED
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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.