Originally Posted by petr_rsti
Same issue with my 2010 e92 335i. The buzzing noise has something to do with the light switch. Put ur ear right up against the radio/centre console, then try turning your lowbeams on and the buzzing noise will appear. This happens when the car is both on and off as long as ur lowbeams are on. If you keep the switch on "auto" or "fully on", the buzzing noise continues. However, if you turn the light switch completely off, the buzzing noise will go away. I have an appointment with bmw on monday morning. Will see what they say. I think it might have something to do with the radio or headlights. Faulty wires maybe...dunno?
I will try this, but reason I ruled out anything electrical is because when I rev, the noise is dependent on rpms.. ( at 1K rpm the noise disappears)