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.
1994 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 diagnostic trouble code. For testing procedures, see TESTS W/CODES article in this section. An out-of-calibration ECT sensor may not set a diagnostic trouble code. Use following procedure to test sensor calibration.
- Remove engine coolant temperature sensor. Refer to the ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION . 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 .
ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION
| Application | Location |
|---|---|
| Prizm & Prizm LSi | On Left Side Of Engine, In 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.