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 MANUALSVOLVO2004V70 L5-2.4L VIN 64 B5244S6REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSCOOLANT TEMPERATURE SENSOR/SWITCH (FOR COMPUTER)DESCRIPTION AND OPERATION
2004 Volvo V70 L5-2.4L VIN 64 B5244S6
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
2004 Volvo V70 L5-2.4L VIN 64 B5244S6SECTION Description and Operation
Engine Coolant Temperature (ECT) Sensor
The engine coolant temperature (ECT) sensor checks the temperature of the engine coolant. The temperature of the engine coolant is required so that the engine control module (ECM) can regulate:
- the injection period
- the idle speed
- the engine cooling fan (FC)
- the ignition advance
- engagement and disengagement of the A/C compressor
- diagnostic functions.
The sensor is a negative temperature coefficient (NTC) type which is supplied with power from the control module (signal) and is grounded in the control module.
The resistance in the sensor changes depending on the temperature of the coolant. Depending on the resistance in the sensor, voltage (signal) is transmitted to the engine control module (ECM). The lower the temperature the higher the voltage (high resistance). A high temperature results in low voltage (low resistance).
The engine coolant temperature (ECT) sensor is located beside the thermostat.
The engine control module (ECM) can diagnose the engine coolant temperature (ECT) sensor. The sensor value can be read off using VADIS/VIDA.
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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.