One problem related to air bag light on has been reported for the 2013 BMW 328. The most recently reported issues are listed below.
It seems that I have damage to my valve cam, well just looked up and the vehicle was involved in an accident that was never reported to me at the time of purchase - I am looking at paying over 1700 for a valve cover (labor and material). My air bag lights came on in July and I am told that my VIN is not under recall - when I took to mechanic I was told to take to BMW to have added to recall.