03-03-2007, 10:31 AM
just got my certified pre-owned 2004 bmw 530i yesterday. i open he door and i hear a low pitch humming/ buzzing sound in the engine compartment which eventually goes off. after i drive the vehicle and lock the doors, the low pitch humming/ buzzing sound turns back on. the noise eventually turns off by itself. is this something to be concerned about or is this a typical thing?