Quiet motor noise on a C5 when switched off

[detheridge]

Hi folks,
I've just purchased a 57 plate C5 2.2 auto, with the usual niggles of heater flaps - from postings here a common fault.

However, one curious thing that I've never encountered before is that when the ignition is off there's a quiet humming from behind the passenger side of the dashboard. You can only hear it with the doors closed. Obviously something's still running even after switching off and removing the key. It's not a fan in the engine, but it has been suggested to me that it could be one of the myriad relays behind the console, or something to do with the EGR valve. If I disconnect the battery it stops, but obviously I don't want to have to reconnect every day and reset everyhting on the Navidrive each time.
So - any ideas folks?

Best wishes,
David.

[Homer]

Ours would hum until the doors were locked. No idea what it was, just assumed it was normal behavior.

[Michel]

It's just all the systems shutting down, the noise will stop after a minute or so once you get out the car and lock it, or at least it should. Both my C5s, C4 and C4 Grand Picasso did it to some extent. My Skoda Octavia also does it

[Subsonicnat]

Maybe the same adage,,Does the light go OFF When you close the fridge door.lol.

[GiveMeABreak]

However, one curious thing that I've never encountered before is that when the ignition is off there's a quiet humming from behind the passenger side of the dashboard. You can only hear it with the doors closed. Obviously something's still running even after switching off and removing the key. It's not a fan in the engine, but it has been suggested to me that it could be one of the myriad relays behind the console, or something to do with the EGR valve. If I disconnect the battery it stops, but obviously I don't want to have to reconnect every day and reset everyhting on the Navidrive each time.

Ignore it. It is in fact the EGR valve resetting to default position after the engine is stopped.

[detheridge]

Many thanks for the replies folks - I can breathe easly again! The thing was that this was new for me because my former 2003 C5 Exclusive (2.0 litre 8 valve) never did anything like this.

[myglaren]

Many thanks for the replies folks - I can breathe easly again! The thing was that this was new for me because my former 2003 C5 Exclusive (2.0 litre 8 valve) never did anything like this.

I had to fit a new headlamp bulb in mine a couple of weeks ago and heard something similar.
Ignored it and it went away





Engine will probably fall out now.

[GiveMeABreak]

Many thanks for the replies folks - I can breathe easly again! The thing was that this was new for me because my former 2003 C5 Exclusive (2.0 litre 8 valve) never did anything like this.

Depends on the engines / year / technology used. Later models and engines use a lot more of these electrovalves and with the addition of particle filters they are also used with regeneration.

[crapday69]

my mk2 C5, C4 and x7 C5 have all done this. I never worried about it, just thought it was the car getting ready for shut down.