[alFR]

Last couple of days I’ve noticed a strange noise from the dash area immediately after getting into the car. It’s very quiet, medium pitch, almost sounds like an electric motor running. Lasts about 30-40 seconds then stops. Not audible over the engine noise after starting up. I’ve not been able to localise it any more than that it seems to be coming from the dash and I’m pretty sure it wasn’t doing it before. It doesn’t happen every time I get in either, I haven’t worked out if there’s a particular pattern to it yet (e.g. if it only does it after the cars been sitting for a while). Anyone heard similar or got any idea what it might be?

[The_Tok'Ra]

Originally Posted by alFR

Last couple of days I’ve noticed a strange noise from the dash area immediately after getting into the car. It’s very quiet, medium pitch, almost sounds like an electric motor running. Lasts about 30-40 seconds then stops. Not audible over the engine noise after starting up. I’ve not been able to localise it any more than that it seems to be coming from the dash and I’m pretty sure it wasn’t doing it before. It doesn’t happen every time I get in either, I haven’t worked out if there’s a particular pattern to it yet (e.g. if it only does it after the cars been sitting for a while). Anyone heard similar or got any idea what it might be?

Have you tried turning off your heating, see if the noise goes away, before you even start the car? could be a motor or fan bearing that's a bit dry and sitting for a few days, it gets a bit sticky and makes a noise, then frees up once it's be spinning for a bit of time.

[alFR]

Will try turning the AC off, although it doesn’t sound like a fan really: it’s audible as soon as I get in, before I’ve touched the start/stop button and there’s no sound of air movement associated with it. Will see if I can localise it a bit better.

[The_Tok'Ra]

Originally Posted by alFR

Will try turning the AC off, although it doesn’t sound like a fan really: it’s audible as soon as I get in, before I’ve touched the start/stop button and there’s no sound of air movement associated with it. Will see if I can localise it a bit better.

Could be a solenoid for "something". These cars are so damned complicated now, it's hard to figure anything out.

I'm so glad I managed to get my creaking steering wheel sorted under warranty, that was a simple bit of trim rubbing as the clips that hold the silver wheel faceplate were broken, but how that was broken in the first place is beyond me.

The only thing I can think of is the the previous owner thumped the horn so hard it broke the clips around the trim.

EDIT:- Actually, if it's been sitting for a few days it might just be the fuel pump running to build up a bit of pressure in the fuel line before you start the car. My 325 Compact does that, and it's normal if the car has been sitting for a while, but then it runs for maybe 10 - 20 seconds, not 40.

[alFR]

Managed to get a short video clip with the sound on it. I took it when getting into the car this AM after it sitting overnight. You will need to turn the volume up a bit, it's quite faint but audible and you can hear it stop about 5-6s before the end of the video. Still can't work out a pattern to when the noise occurs: tried to record it twice yesterday during the day (lunchtime and when I finished work) but it didn't make the noise either time. I have also noticed the same noise intermittently after turning the car off. The a/c is off in the clip and there's no fan noise so I don't think it's related to that. I'm stumped, but everything seems to be working OK so ?

[G21MKN]

This is a thread I posted a video about a year ago which sounds similar. I’ve never worked out what the ‘hum’ is and everything works as should. It is also intermittent.

https://g20.bimmerpost.com/forums/sh....php?t=1942214

[alFR]

Can’t see the video in that thread, can you re-link it?

[sjb993]

Have you tried listening for it in the engine compartment with the bonnet up?

[Assassin]

Most likely the air conditioning system preparing to get the car to your specified requirements within the parameters set for fan speed etc. The system tries to get there as quickly as possible so flaps, fan speed etc will be activiated to get there. It will react differently depending on the difference between current conditions and your settings hence the intermittent aspect of the noise. Can be most noticeable if you have set it on Auto with a high fan setting as it can run up to the right up to that fan setting until the correct conditions are reached and then it will back off to maintain the optimal temp etc.

[Riccardog]

I (think - have not listened to the video yet) that I have the same noise on my 320i. Its been there for over a year and so faint I just ignore it.

Curious if you ever figure it out!

[supest]

I'm pretty certain this noise is related to the air conditioning system. I've had this noise on both the 5 and 3 series. If you have the air con on and then switch it off after a short drive, you can replicate the same noise.

Don't think this is a concern/ malfunction of any sort.

[330Stevie]

Yep, defo aircon system matrix opening up. It closes vents etc after car goes to sleep also
Pretty sure the manual makes reference.

[DravitPlay]

I listened to mine yesterday after reading this and it makes the same “electrical” noise. I believe it’s just the systems powering up after an extended sleep! It might even be your individual settings being applied. 🤷‍♂️

[alFR]

Yeah, I think it’s the aircon as suggested by supest and stevie above.