Why My Car's Radiator Fan Runs When Car is Off

February 3, 2024

After you drive a car and turn off the engine, you probably notice that the fan in your engine bay stays on for a few minutes. This is normal and is designed to keep the coolant moving in order to help the engine cool down.

The radiator fan is controlled by a temperature sensor that sends the signal to turn it on when the engine reaches a specific temperature. The sensor is connected to the fans via a relay. If this relay is faulty it may cause the fan to run after the engine is turned off. In this case the coolant will stay trapped in the head and may boil over if it isn’t circulated by the fan.

This is why it is important to have the relay replaced if the problem persists. A professional mechanic can diagnose this and repair it for you.

If you find that your car’s cooling fan is running for more than 10 minutes after you shut off the engine, this is a sign of an electrical problem with the fan motor. This will drain the battery and needs to be fixed immediately.

Another reason the fan might be staying on after your engine is turned off could be because you have a low coolant level. This will make the engine hot and require the fan to work more frequently to cool the engine. If you have a low coolant level, it is recommended that you add some.


Traffic Dave is on a mission to help traffic engineers, transportation planners, and other transportation professionals improve our world.
linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram