What The Hell Is It?

[M0JFK]

Got here a 2.2 HDI C5 2001 and inside at the rear drivers side  on the top of the airbag cover is a 3 inch long (rich tea shaped plastic thing) its black, got a separate red and yellow led lite on it and in the middle a kind of sensor the size of a 1 pence piece with a little hole in the middle? Nothing in the driver/owner manual about it so what the hell does it do? Is this common on the executive model or as someone put this thing there at some time in its life? any ideas folks?

[paul.h]

Which air bag is it on ?

[M0JFK]

It Is on the drivers side rear pillar (rear passenger drivers side) on top of the airbag cover...no lights come on it when I activate the alarm so don't think it as anything to do with that Paul...just does nothing, does not make any sounds or bleeps if the thing in the middle is some sort of buzzer...got me stumped and I am usually good with electronics and builds because of my amateur radio hobby but I cant suss what it is. Don't want to start dragging off panels to the ABS and start causing myself more headaches with this car...I like a challenge but don't invite them if you get my drift...lol

[paul.h]

First thoughts are it is an aftermarket parking sensor buzzer and warning lights. If you look in the boot there may be some wires that look as if they go towards it. We had an aftermarket parking sensor kit put on our C3 and the garage stuck the buzzer in a top rear corner but it does not have any lights on it. In a 2003 C5 brochure though it has the exclusive model includes rear parking sensors as standard - if you have these the passenger door mirror will automatically move down to show the kerb when you select reverse gear, provided the door mirror switch is left in the passenger mirror position.

[Xsaradope]

Could be the indicator buzzer/chime that tells you that the indicator lights are working when you are towing a caravan.