I recently replaced a leaky thermostat housing on my '12 Countryman S with 85K miles. I wasn't getting any overheating codes or CEL's, just a small amount of coolant on the garage floor.

Everything installed smoothly enough, and I used the bleeder on the housing to bleed off any air pockets a few times. After at least a dozen heat cycles I'm still getting high coolant temps. I verified today that the low speed fan comes on at 226F and the high speed fan is also working as the temps climb a little higher.

What puzzles me is why the car doesn't cool down once the low speed fan starts up. The coolant temps continue to slowly creep up and bounce cycle between 237-242F. My wife was driving it the other day and she got the yellow CEL for high coolant temp, but it went out within a minute. I scanned the car for any stored codes and there weren't any.

Any suggestions on possible cause?

 

We had the same problem today. Driving on the high way the yellow overheat light came on and told me to drive to cool engine. Then the red, so I pulled over and shut car off. Checked under hood, no leak or boiling overflow. Then restarted car and all was fine the rest of the day. 2013 Countryman S all4 72,000 miles.

 

I removed the aftermarket coolant temp sensor and reinstalled the OEM sensor and the temps have dropped to normal. The temps are now staying at 226F or below. Looks like the aftermarket Amazon coolant temp sensor was causing issues.

 

Good info, I think ours may be failing too.

Thanks!

 

That is funny because we have a 2012 Countryman also and had the original exact same issue as the thermostat housing was leaking coolant but not overheating in the fans were running fine. Two months ago I replace the thermostat housing with another housing and had to use the wiring adapter for the housing that split the main harness and for two months everything was perfect until about two weeks ago we're now we start seeing the yellow light come on showing it may be running hot. Like other said previously I had the wife shut the engine down so there was no potential damage. Sometimes it happens and sometimes it does not. Sometimes the cooling fan will run even when the engine is cold and sometimes it stays on for 10 minutes after the engine has been shut down. As far as I can tell there are no overheating issues because you do not hear the coolant boiling or bubbling. However I did replace the coolant temperature sending unit with another one and had the same issue so I'm not sure what our situation is right now.

The replacement coolant sensor I replaced in the replacement stat housing was an OEM BMW part. I may just replace the entire housing again and go through the electrical connections

 

We are dropping off ours at mini dealer today, I will ask what the deal is with this and let everyone know what they say.

 

So, the deal told me I have a leaking thermostat and it is not covered under warranty. I will be doing it myself. Where did you get the part from? I know build date is a key point. Ours was 03/18/2013.

 

For me, when I did ours on the wife's Mini, I ordered one that I thought was it but the coolant temperature sensor was straight up and would hit the intake or the side of the block and I had to take it back and reorder one where the coolant temperature sensor was at an angle so it would clear. So just be a bit careful on which one it is you need and if you need the wiring harness or adapter to go with it.

 

Did you replace the pipe too? MINI is telling me i need to, but $100 for a pipe seems like alot

 

I guess it should be replaced while you're doing the housing but I did not replace ours only because at the time I did not think about it into technically it wasn't leaking from the pipe

 

Hate to bring up an old thread, I'm having the exact same issue on my '12 R60 SA4
Which sensor was it? the one in the housing or the one in the metal elbow under the air intake?