One of the most common problems you may experience with a BMW overheating or running hot are issues with the cooling fan motor, fan control module, fan clutch, or condenser fan motor. This is caused by overheating your engine by running it past 3/4 on the temperature gauge (3/4 equals 220 degrees). If this happens, STOP and call a tow truck immediately! Do not try to make it to the next exit or gas station. Driving longer could completely ruin your engine.
The cost of a cooling fan runs anywhere between $150 and $475. The exact price depends on the exact year and model of your vehicle.