So I've only owned my car (2008 535xi AT) for a little over a month, but I notice that when I open the driver's door (the one I usually open, obviously) I hear, sounds. Sometimes it's similar to the dual vibration noise of a text message, other time it's almost a feint air compressor or air relief type noise. I'm pretty sure my car has the comfort package (as I came out one morning with all the windows open/down, (teach me to keep my fob in my pocket for too long).

If there's any information I can provide, let me know. I guess I'm concerned about excess battery drain or the like, dunno.

Thanks.

 

also interested in this info because my car does the same thing, it usually does it in the garage when I open the door a few moments later and also when I close the door a few moments later there's an air compressor hum/sound from the trunk. MIne is a 2008 528i

 

I wonder if the lumbar support is pnuematic and somethings triggered when the door's opened.

 

It is various parts of the car waking up. Like your presets, seats, steering wheel, computer, modules. And yes there are some of them in the trunk.

 

^yup...the car will make the same sounds if it's locked and you push the button in the trunk lid to try and open it.

 

To me it sounds like the fuel pumps priming themselves when you wake up the car. My Audi does this as well.

 

ding ding ding, winner!

It's the fuel system energizing. My '04 does it as well.

 

I will only add that if you don't hear that noise when you open a door or trunk or hood after the car sits for 20 min, then you may have a problem. The car is not going into sleep mode, and it may be running out the battery.

Psam550

 

Agreed! Think it is the DMTL Pump.

 

Yes, the DMTL pump definitely comes on whenever I open a door. I think the in tank pumps may prime themselves too, but the DMTL pump is so loud it drowns anything else out.