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.
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HOMESERVICE MANUALSHYUNDAI2003SONATA V6-2.7LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSCOOLANT TEMPERATURE SENSOR/SWITCH (FOR COMPUTER)TESTING AND INSPECTION
2003 Hyundai Sonata V6-2.7L
Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection
2003 Hyundai Sonata V6-2.7LSECTION Testing and Inspection
ENGINE COOLANT TEMPERATURE (ECT) SENSOR
The engine coolant temperature sensor installed in the engine coolant passage of the cylinder head detects the engine coolant temperature and emits signals to the ECM. This part employs a thermistor which is sensitive to changes in temperature. The electric resistance of the thermistor decreases in response to a temperature rise. The ECM determines engine coolant temperature by the sensor output voltage and provides optimum fuel enrichment when the engine is cold.
USING MULTI-METER
1. Remove engine coolant temperature sensor from the intake manifold.
2. With temperature sensing portion of engine coolant temperature sensor immersed in hot engine coolant, check resistance.
3. If the resistance deviates from the standard value greatly, replace the sensor.
TROUBLESHOOTING HINTS
If the fast idle speed is not enough or the engine gives off dark smoke during the engine warm-up operation, the engine coolant temperature sensor might be the cause.
The engine coolant temperature sensor installed in the engine coolant passage of the cylinder head detects the engine coolant temperature and emits signals to the ECM. This part employs a thermistor which is sensitive to changes in temperature. The electric resistance of the thermistor decreases in response to a temperature rise. The ECM determines engine coolant temperature by the sensor output voltage and provides optimum fuel enrichment when the engine is cold.
Circuit Diagram:
Using Hi-scan:
USING MULTI-METER
1. Remove engine coolant temperature sensor from the intake manifold.
2. With temperature sensing portion of engine coolant temperature sensor immersed in hot engine coolant, check resistance.
3. If the resistance deviates from the standard value greatly, replace the sensor.
Harness Inspection Procedures:
Using Voltmeter:
TROUBLESHOOTING HINTS
If the fast idle speed is not enough or the engine gives off dark smoke during the engine warm-up operation, the engine coolant temperature sensor might be the cause.
RENDER: 1.0x
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.