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.
1995 Geo Prizm Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Engine Coolant Temperature (ECT) Sensor
- A malfunction in the engine coolant temperature sensor circuit will set a related DTC. For testing procedures, see TESTS W/CODES - 1.6L article. An out-of-calibration ECT sensor may not set a DTC. Use following procedure to test sensor calibration.
- Remove engine coolant temperature sensor. See ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION table. Using ohmmeter, measure resistance of engine coolant temperature sensor at designated temperatures. Replace ECT sensor if resistance is not within specification. See ENGINE COOLANT TEMPERATURE (ECT) SENSOR RESISTANCE table.
ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION
| Application | Location |
|---|---|
| Prizm | On Left Side Of Engine, In Engine Coolant Housing |
ENGINE COOLANT TEMPERATURE (ECT) SENSOR RESISTANCE
| Temperature °F (°C) | Ohms |
|---|---|
| -4 (-20) | 10,000-20,000 |
| 32 (0) | 4000-7000 |
| 68 (20) | 2000-3000 |
| 104 (40) | 900-1300 |
| 140 (60) | 400-700 |
| 176 (80) | 200-400 |
Factory Service Tools
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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.
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