[jayartibee]

My mirrors come on and warm up fine - but only, I think, below 5°C - is this the normal experience of others? It is annoying when it's mild but damp

 

[jwilalex]

Fairly sure BMW default for auto heated wing mirrors is outside temp at 3 deg or below.

 

[jayartibee]

and then someone on the US site just said that auto-wipers need to be on. Confusing!

 

[jayartibee]

Actually I now find this as a service bulletin so maybe I've answered my own question. Quite different to an e46

The door mirror heating is controlled dependent on the outside temperature and whether the wipers are switched on.

With wipers switched off:
Below 5°C = 100% continuous heating
Above 5°C = 0% heating

With wipers switched on:
Below 5°C = 100% continuous heating
From 5 to 10°C = 75% heating
From 10 to 15°C = 50% heating
From 15 to 20°C = 25% heating
Above 20°C = 0% heating
Customer booking status
Booking status - No Booking
There is no fault with system operation. Customers should be informed that this is how the door mirror heating function operates.
However, if the customer’s car is installed with automatic rain sensor (option code 521) suggest that the wiper switch could be set to the automatic interval position in order to benefit from maximum heating function of the door mirrors