While I know that on hot days or after some hard driving, the engine cooling fan will stay on for a while after the car is turned off...

But lately my R58 (N18 with 40k miles) cooling fan has come on and stayed on almost every time I drive.

This morning, around 75 degrees outside, cold start, I gently drove 1.5 miles to go get some coffee. Even with such conditions and short drive, the cooling fan stayed on after I turned off the car for at least a minute or two.

I check the coolant level and it's just a little below MIN line but I don't know...could there be some other issue? Thermostat or something?

 

auto or manual?

top off the coolant and see if that helps it.

 

Could be a temp fault in the thermostat.

Do you have the AC on? The fans will run on low speed and kick up to high speed once a minute to keep pressures in check, and it's not uncommon for the fans to stay running for a bit after shut down to stabilize pressure in the system.

Have you recently been in for service on the cooling system? If the car is an automatic and there was a temp fault stored in the ECU it is also stored in the trans control unit and will continue to cause problems until the codes are cleared from the TCU as well.

 

Thanks for the responses. Mine is manual. I didn't have the a/c on for that short drive, but on longer drives I do and then the cooling fan is spinning so fast I can feel it like it's shaking the car.

I'll top off the coolant and see how it goes, but is there any way to easily check if the thermo is broken or not?

 

Does the car leak coolant? That would indicate a cracked thermostat housing or failed gasket if the leak is in that area.

As for failed thermostat you'll either overcool or over heat, either of which should throw a CEL for a temperature deviance, and in the case of an overheat a temperature light.

 

***UPDATE***
I checked again and there are no leaks, and everything looks fine....

I connected my OBDII scanner this morning. Cold start, around 60 degrees F outside, and the coolant temp reading was 151 F which is obviously not possibly correct.

I read the diagnostics code and there was a "pending" code P10D5

I searched here and there is no mention of this code at all, which is odd. A broader google search showed that it means "Coolant temperature sensor, cold start: Coolant temperature too high."

Anyone ever have this pending code? Any ideas what to do next as far as troubleshooting? OR just go ahead and buy a new coolant temp sensor ?

 

Temps sensor is cheap, takes 5 mins to change out. Sometimes it is a dodgy connection, before buying a new sensor, try unplugging the connector and give the pins in the sensor a clean with a cotton bud, push the connector on firmly. Mine was cured this way. If that fails then pull the metal clip, remove old sensor and quickly insert the new one to avoid losing fluid. Use a new sealing ring. (Obviously do this on a cold engine :-) Clear codes. Last tip, unscrew the bleed screw a couple of turns just in case there is a small airlock in the top of the thermostat.

 

^^+1