Thermistor Switch Replacement Guide: DIY Car Repair You Can Do Yourself

If your car’s radiator fan is behaving strangely—running nonstop or not turning on at all—one component you should suspect is the thermistor switch . This small part controls when the cooling fan turns on and off based on engine temperature. In this post, we’ll walk you through how to locate, replace, and test a thermistor switch yourself, along with tips, tools, and safety precautions to make it a successful DIY repair.     1. When Should You Replace the Thermistor Switch? Radiator fan keeps running after engine shutoff Fan turns on even when the engine is cold Fan does not turn on, causing engine overheating Engine warning light or cooling fan control DTCs (Diagnostic Trouble Codes) 2. Where to Find the Thermistor Switch The switch location varies by vehicle, but it is commonly found in: Lower or side section of the radiator Near the thermostat housing On or around the cylinder head     3. Tools and Mater...