I had this trouble a while ago on my 2012 N18 MCS before the thermostat swap.
A poster on NAM gave a very good explanation of what the trouble seemed to be because it seemed to occur more in the US, possibly encouraged by a warmer climate? Also I seem to remember they found some wiring which came rather too close to hot engine parts in one of the new variants which certainly coincided with the temp sensor repositioning 'fix/recall'...
"To understand what is going on here, you have to understand that there is a temperature sensor that tells the ecu what the temperature is, and a mechanical thermostat that opens at a certain temperature and regulates water flow and therefore the temperature.
What is supposed to happen is that the mechanical thermostat is set to 105C (221). When the car is moving with good radiator flow the temp should stay at roughly 105. Once the temperature goes > 106 (223) the electric fan cuts in. This usually because the car is stationary, with no airflow.
The problem is that the mechanical thermostats seems to be a little inaccurate and out of sync. There are a whole lot of thermostats that seem to run at 107-108C (224-227F). What happens in this instance is the thermostat doesn't open water flow properly until it reaches its temp, so driving around the temp will be 107-108C. This confuses the ecu, as the temperature sensor reads >106, so it activates the fan.
It is also possible to have the reverse problem, ie an accurate thermostat but a miscallibrated temperature sensor which reads the water temp higher than it actually is, which can produce exactly the same problem.
If this is happening, the fan is not just running when you stop the car, but nearly all the time, even driving around. When you stop it will run until the temp drops to the 106C number.
So if you are lucky and have a "normal" thermostat that runs around 104-105C you won't get the fan operating when you stop very often. If you have one of the thermostats that runs at 106-108C you will get it a lot."
It seemed there was a quality control mismatch.
BTW the loud 'second stage' fan will usually come on for a while (always much less than 5min for me) after you've had the air-con on...
Last edited by cjm; Jan 24th, 2016 at 08:34 AM.