Quiet motor noise on a C5 when switched off

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detheridge
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Quiet motor noise on a C5 when switched off

Post by 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.
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Re: Quiet motor noise on a C5 when switched off

Post by Homer »

Ours would hum until the doors were locked. No idea what it was, just assumed it was normal behavior.
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Michel
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Re: Quiet motor noise on a C5 when switched off

Post by 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
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Re: Quiet motor noise on a C5 when switched off

Post by Subsonicnat »

Maybe the same adage,,Does the light go OFF When you close the fridge door.lol.
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GiveMeABreak
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Re: Quiet motor noise on a C5 when switched off

Post by GiveMeABreak »

detheridge wrote: 12 Feb 2019, 07:11 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.
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Marc
detheridge
Posts: 51
Joined: 25 Nov 2013, 12:13
Location: Ludlow Shropshire
My Cars: '03 C5 2.2 Exclusive Estate.

In the past:
'07 C5 VTX+ 2.2. 170hp Estate auto
03 C5 2.0 Exclusive Estate.
95 XM 2.5D Exclusive
94 Xantia 1.9D Estate
92 XM 2.0i
90 XM 2.0
Various CXs (CX22, CX Pallas, CX GTi, CX Estate)
81 GSA Pallas
1974 DS23 Estate
1974 DS23 Pallas
1970 DS21 Pallas EFI
x 3

Re: Quiet motor noise on a C5 when switched off

Post by 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. :-)
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Re: Quiet motor noise on a C5 when switched off

Post by myglaren »

detheridge wrote: 12 Feb 2019, 10:26 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.
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GiveMeABreak
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C5 MK II 2.0 HDi Exclusive Obsidian Black
C5 MK I 2.0 HDi SX Wicked Red
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C15 Romahome White
XM 2.0 Turbo Prestige Emerald Green Pearlescent
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XM 2.0 SX Polar White
CX 20 Polar White
GS 1220 Geranium Red
CX 2.4 Prestige C-Matic Nevada Beige
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Re: Quiet motor noise on a C5 when switched off

Post by GiveMeABreak »

detheridge wrote: 12 Feb 2019, 10:26 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.
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Re: Quiet motor noise on a C5 when switched off

Post by 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.
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