7 series noise

[Tom8]

Hi,

I have a 730D 2010. Coming home tonight noticed a rumble almost like another engine in the car. Got home and it is a noise seeming coming from the boot or under it. It is like a motor running but won't stop with engine or ignition off. Any idea what it is?
Thanks

[outnumbered]

Air suspension pump ?

[Tom8]

outnumbered said:

Air suspension pump ?

Does it sit under the boot? Seems like it won't turn off albeit I got in and moved it a touch then it finally turned off again.