17 00... Notes on retrofitting a trailer towing device
WARNING: This page is about a different car, the 2009 BMW 528xi, 2009 BMW 528i, 2008 BMW 528xi, and 2008 BMW 528i. However, it is still accessible from the selected car via links, so may be relevant.
Starting with delivery of the E90, in certain vehicle types, the size of the electric cooler fan will be linked to the optional extra trailer tow hitch or trailer provision.
The larger fan is necessary to ensure mountain driving with a full trailer load in accordance with BMW-internal specifications. Otherwise the engine electronics will detect possible overheating of the cooling system and activate protective functions.
For the customer, this involves impaired A/C output, automatic transmission and engine power. These will be continuously reduced, which in the end may result in the vehicle coming to a standstill in the mountain area.