Similar thing happened to me, I'm also assuming it's one of the wheel sensors. Mine stayed on after hitting a big pot hole. You may just want to have a Bimmer shop reset the ABS system. It's supposed to just take a minute and they may do it free. I tried to do mine using a Bav Auto reset tool to no avail. I have just left mine at fault, cause I installed a MOMO wheel anyway (no more airbag)! The MOMO wheel gave me much more leg room as I am 6'4" and needed that extra room to do my "clutchwork".