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.
Coolant Temperature Sensor (CTS)
If a coolant sensor-related code is present, see the appropriate G - TBI TESTS W/ CODES article (for Throttle Body Injected models) and G - PFI TESTS W/ CODES article (for Port Fuel Injected models) in this section. An out-of-calibration sensor may not set a trouble code. Use following procedure to test sensor calibration. Disconnect coolant temperature sensor connector. Measure resistance between sensor terminals. Resistance should be high when engine is cold and drop as engine warms. See CTS RESISTANCE VALUES table.
| °F (°C) | Ohms |
|---|---|
| 210 (100) | 185 |
| 160 (70) | 450 |
| 100 (38) | 1800 |
| 70 (20) | 3400 |
| 20 (-7) | 13,500 |
| 0 (-18) | 25,000 |
| -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.