Possible Fault Causes
WARNING: This page does not describe the selected car, but rather 53 other vehicles, including the 2013 BMW X6 M, 2013 BMW X5 M, 2013 BMW M6, 2013 BMW M5, and 2013 BMW Alpina. However, it is still accessible from the selected car via links, so may be relevant.
-Mechanical defect in radiator vent slat assembly (broken linkage)