Ok here’s  a little annoying bulb sockets,reverseproblem on a M4,,,the reverse light going out,,,,when you remove the bulb socket you will find it damaged and broken. This is what happens when you take the reverse bulb sockets out,,,you can see the metal contacts for the sockets came apart,,,,also the bulbs get burnt out because of the bad contacts,,,,so BMW has redesigned them with better bulb sockets and new bulbs.