17 00 ... Notes on retrofitting a trailer towing device

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. A larger fan may therefore be required for retrofits. 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.