Q: Electric Cooling Fan Remains On Even When Car is turned off

asked by on July 31, 2017

Hello, I have a 2015 Toyota Yaris L Hatchback, after I got an oil change from the Toyota dealership the next day my car wouldn't start. The battery was drained, we bought a new battery and the next day it goes dead again. After jumpstarting the car we realized that the electric cooling fan remained on even when the car was turned off, remaining on for hours until it drained the battery. We checked the fuse for the cooling fan and there was no short, but the fan still keeps running. Is there any other issue that would prompt the fan to remain on? What could the problem be? Could it be a bad coolant temperature sensor? Or faulty relay? The dealership can't replicate the problem and can't fix anything because no trouble codes come up on their computers. Thank you for taking the time to answer my question- Paul V.

My car has 43000 miles.
My car has an automatic transmission.

The radiator fan will be controlled by the engine ECU (electronic control unit) through a relay. The relay is most likely your problem. When the fan shuts off, it can cause a small arc on the relay points that will weld them together and keep the relay and therefore the fan turned on. Replacing a fan relay is not a big deal and here is an article to help you through it. If you don’t want to try it yourself, contact Your Mechanic. They can send a technician to your home or office to replace your fan relay right there on the spot.

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