Have now checked for any "vents" around the computer units and found it very enclosed. I actually tighted the cover even more to at least shield for heat coming in...
Here are two other longshots; the problems started after a service where the battery was disconnected. At the same time they fixed the cruise control, that was not working at all, but now works from 40 to 110 km/h, over that it will not engage. Is this normal? The outside thermometer did go down from ordinary readings to exactly ten degrees lower. I suspected it to be something in connection with temperature shift during the time the battery was disconnected. A sort of accidental calibration. Is this possible and can it be calibrated at all? Can the thermometer misreading or the CC limitations affect my ECU to put the car into limp mode?
The MB garage guys just shake their heads but they seems to know absolutely nothing when they get no fault codes.
Fortunately (for me) the midsummer weather here in Scandinavia is cold and wet so the car is working just fine for a couple of days!