Skip to Main Content

How Does an Engine Coolant Temperature Sensor Work?

Published Thu January 26, 2017

temperature sensor on a car


How hot does your vehicle’s engine get during an average drive? 

You may not know—but hopefully, your vehicle coolant temperature sensor does. The sensor keeps tabs on the operating temperature and alerts the on-car computer when there’s a potential problem. But how does this car temperature sensor really work—and what’s its purpose? 


How the Temperature Sensor Works


On most vehicles, the coolant temperature sensor (CTS) can be found somewhere near the engine thermostat, which allows it to function optimally. The tip of the CTS is probably located right next to the engine coolant.

The sensor works by measuring the temperature that’s being given off by the thermostat and/or the coolant itself. The temperature is then sent to the on-board control system. From there, your vehicle’s computer will use this temperature information to either continue operating or adjust certain engine functions, always working to keep the engine temperature at an ideal level.

As the control system receives the temperature from the CTS, it may trigger the cooling fan to either shut off or turn on. Additionally, it may signal the need for a richer fuel mixture or open the exhaust gas recirculation.


When the Car Temperature Sensor Goes Bad


As with any other component in your car, the sensor can go bad over time and fall into disrepair. This can cause a range of problems, including overheating the engine.

If you know where the engine sensor is and what it looks like, you can conduct a visual inspection to see if it has developed any cracks or fissures. While this visual check can be helpful, it won’t help you diagnose every possible problem as some sensor malfunctions can present without visual evidence.

Generally speaking, if your sensor is not working, it will send a signal to the computer and your Check Engine light will be illuminated. If you see the Check Engine sign light up, take your car in for professional servicing right away.


Replacing the Car Temperature Sensor


The sensor will eventually need to be replaced altogether after time. If the engine sustains any kind of trauma or damage, sensor replacement is always recommended because you don’t want to risk running the vehicle with a faulty one. Even general wear and tear can cause the sensor to erode over time.

You can always have your CTS replaced by an auto care professional. This aspect of preventative maintenance can certainly save you some headaches and hassle in the long run.

Hint – if you can’t find a temperature sensor in your car – this article should help.