How a Coolant Temperature Sensor Works How a Coolant Temperature Sensor Works

The engine coolant temperature sensor (ECT sensor) is a temperature sensor in a car’s engine that essentially determines and measures the temperature of the engine. The information received from the coolant temperature sensor is then used to regulate the temperature of the vehicle’s engine. 

Coolant Temperature Sensor – How it Works

The coolant temperature sensor (CTS) is often located near the thermostat of a vehicle’s engine so that it can operate at its optimum level. The tip of the coolant temperature sensor is generally located directly near the coolant of the engine.

This temperature sensor works by measuring the temperature that the thermostat or coolant is giving off. The temperature that the sensor reads is then sent to the on-board computer or engine control system as a signal. The engine control system then uses the information it receives from the coolant temperature sensor to operate or adjust some of the functions of the engine for it to run at its optimum level.

Aside from regulating the temperature of the engine by turning the cooling fan on and off, the information received from the temperature sensor is also used to determine if the engine needs a richer fuel mixture, to ignore the oxygen sensor rich/lean feedback signal, to open the exhaust gas recirculation or to limit the spark advance during emission.

Determining a Faulty Coolant Temperature Sensor

A faulty coolant temperature sensor can cause a whole lot of problems for the engine so it is important that the sensor is always in good condition. Generally, looking at the sensor itself will help determine if the part is faulty. However, this will only determine the visual damages one can see like a crack, leak or corrosion in the sensor.

A Digital Volt Ohm Meter (DVOM) can also be used to the internal resistance of the sensor. The reading can then be compared to the normal specifications. If the reading is within specifications but a problem is still evident, then the problem is in the wiring.

However, one of the best ways to determine if the coolant temperature sensor is faulty or malfunctioning is to look to see if the check engine light is on. In the event that the temperature sensor is not functioning properly, the computer in the vehicle’s engine will send a signal. The data is then used to provide a trouble code which will turn on the check engine light.

Replacing the Coolant Temperature Sensor

A coolant temperature sensor can age and deteriorate in time so it is important to know how to replace a faulty temperature sensor. Replacing the CTS is often advised when rebuilding an engine and when it is damaged.

The engine should be allowed to cool first before the sensor is replaced. The coolant in the cooling system should be drained before replacing a coolant temperature sensor. However, do not drain the radiator. Draining just some of the coolant is enough. Open the valve to drain the antifreeze.

Once the coolant is drained, replace the old sensor with a new coolant temperature sensor. It is important to remember to refill the radiator with coolant.

Got a New Project You're Proud of?

Post it on Your Projects!