Volkswagen Engine Temperature Warning Light

When Should You Replace the Coolant Temperature Sensor in Your VW?

by admin May 1, 2020

An engine needs to maintain a temperature within a certain window in order to operate effectively and avoid damage from overheating. What keeps things cool in your car is a heat-absorbing fluid called coolant that circulates throughout the engine. The piece of technology that monitors the coolant is called the coolant temperature sensor or coolant temperature switch. This sensor needs to be working effectively or your Volkswagen may begin to overheat.

This article will cover the function of the coolant temperature sensor, symptoms of its failure, and answer the big question: When should it be replaced?

The Purpose of the Coolant Temperature Sensor

The coolant temperature sensor works in conjunction with several other parts of the vehicle. It communicates with the powertrain control module, which plays a critical role in engine performance.

The sensor measures the temperature of the coolant in your vehicle, which absorbs the heat from the cylinder heads in the engine. They house the combustion that gives your engine power. When the engine is working hard, the coolant becomes hot as more heat is created as a byproduct of high combustion levels. The information that the sensor gathers is reported to the powertrain control module, which then makes adjustments to the ignition system.

If the coolant temperature sensor reports a cold reading to the powertrain control module, the module adjusts the air-fuel mixture to make it more rich and burn more fuel. If the sensor reports hot temperatures, the module will make the air-fuel mixture leaner and turn on the engine cooling fan.

Symptoms of a Broken Sensor

There is no specific mile count or amount of time after which a coolant temperature sensor should be replaced but rather some general symptoms. As more miles are tacked on to your VW, the coolant temperature sensor will start to deteriorate.

The sensor is critical to your VW’s operation, so if you notice any of the following issues, be sure to address the problem by visiting a certified mechanic or doing any needed repairs yourself.


As a part of the cooling system in your VW, one sure sign of the sensor’s failure is consistent overheating. If you find that the temperature gauge on your car’s dash is high after even a short drive, it could be caused by a broken coolant temperature sensor. However, there are many other reasons your vehicle may be overheating.

Check Engine Light

If your engine management light or check engine light comes on, it’s usually best to not ignore it. Your vehicle has a way of reporting if something is malfunctioning, and if the check engine light illuminates, there is a chance that it was caused by a broken coolant temperature sensor.

Poor Fuel Economy

If your vehicle starts to guzzle gas, it’s indicative of a bigger problem. The coolant temperature sensor helps your VW run efficiently by keeping things at a consistent temperature. When it fails, efficiency will drop, which you’ll notice not only in your driving but also in your wallet at the gas pumps.

Erratic Temperature Gauge

Not only does the coolant temperature sensor help ensure your vehicle doesn’t overheat, its role is more broadly to keep the heat in your engine somewhat consistent. If the temperature gauge is moving up and down erratically, the sensor could be broken or not working as it should be.

You never really know when something in your engine is going to malfunction. It’s important to keep an eye out for these symptoms. If you notice them, and a mechanic has confirmed that it’s a sign of a broken coolant temperature sensor, it’s time to get the sensor replaced.

McIlvain Motors Can Replace Your VW’s Broken Coolant Temperature Sensor

You shouldn’t let your Volkswagen’s broken coolant temperature sensor ruin your driving experience. Volkswagen Coolant Temperature Sensor McIlvain Motors will carry out a complete and detailed diagnostic report to share with you in order to create a game plan for replacement.

We are located in Tempe, Arizona and proudly serve customers from nearby Chandler, Mesa, Phoenix, and Scottsdale as well. We understand that you want to get your vehicle back on the road quickly, and our unsurpassed service will make sure that your VW is running like normal, without having to charge you an arm and a leg. If you want the expertise of 100 years of auto-service experience, we are happy to service and maintain your VW for all its future needs.