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A faulty coolant sensor in your Volkswagen may not sound like a big deal, but it can lead to the overheating of your engine. If this sensor failure is detected in its early stage, it would save your engine from being strained, and the best part is that replacing it is relatively cheap. Let’s see what this sensor does and how you can replace it to keep your VW running smoothly.
What Does the Coolant Temperature Sensor Do?
The coolant temperature sensor is a component designed to measure the temperature of the coolant in the engine. It provides real-time temperature information to the car’s ECU that in turn controls the fuel/air mixture, the ignition timing, and switches on the cooling fan whenever necessary. If the temperature is high, the sensor signals the system to switch on the cooling fan. It also informs the temperature gauge on the dashboard what to show. Without the help of a properly functioning sensor, the car has no way of determining the true temperature of the engine, which is a bad thing.
Common Signs of a Bad Coolant Temperature Sensor
- Wrong Temperature Display: There are a number of symptoms that point to a faulty coolant temperature sensor and one of them is an erratic temperature reading. The reading can remain in the cold region even when all parts of the car engine are hot, it can rise to hot suddenly, or fluctuate between cold and hot irregularly.
- Overheating Engine: In some cases, a completely failed sensor may not even turn the fan on at all. If the engine overheats because of this, it may lead to serious and expensive consequences if it is not addressed promptly.
How To Diagnose A Failing Coolant Sensor
When diagnosing a faulty coolant temperature sensor, the first step that most technicians would take is to connect a scan tool to check for codes stored in the ECU. These codes assist in identifying the problem and in determining if the sensor is sending the wrong signals. Also, the voltage and resistance of the sensor may be measured using a multimeter. A good sensor should respond to the increase in engine temperature by changing its resistance in a measurable way. If the reading remains constant or does not change with temperature, this is a clear indication that the sensor requires replacement.
How the Sensor Is Replaced
To replace a coolant temperature sensor, there are several procedures that need to be followed.
- Letting the Engine Cool: The first step involves allowing the engine to cool because the sensor is attached to the cooling system and if one tries to remove it while hot, he or she is likely to be burned by hot coolant or steam.
- Locating and Removing the Old Sensor: After the engine has cooled down, the technician then identifies the position of the sensor, which is normally fixed on the thermostat housing or on the cylinder head based on the model. To access it, the electrical connector is disconnected and then the sensor is unscrewed and pulled off. It is also often advisable to replace the sealing O-ring during this process to prevent such leakage in the future.
- Installing the New Sensor and Testing: Before the new sensor is installed, the area is prepared by wiping it, and any previous sealant or debris is cleared. The new sensor is then placed back and tightened to the recommended torque. Once the coolant is added and any trapped air bled out of the system, the car is started to confirm the functionality of all systems and the accuracy of the readings on the dashboard.
Bring Your Volkswagen To Adair & Sons Automotive For Coolant Sensor Replacement
Volkswagen owners in Round Rock, TX, 
and nearby communities can trust Adair & Sons Automotive for reliable, honest repairs when coolant temperature sensor problems occur. Our team of professionals has extensive experience in working with German vehicles and understands the exact measures required to solve this common issue before it escalates into a bigger issue. Whether you want a simple sensor change or a complex cooling system test, our mechanics will ensure your VW is handled in the best way. Come to our workshop in Round Rock and let our professional mechanics fix your VW and make it run as it should – calmly, smoothly, and without any problems.