Help? What is this

[Aircooled]

Hi Guys,
Whilst changing the NS dipped beam bulb, I noticed this when removing the battery, erm, anybody know what it is? What it does? The black box on the left connects to the grey box on the right and they are then screwed on to the bracket in the middle, where it connects to the rubber hose underneath, this is broken.
I have a feeling it`s summat to do with temp/aircon/heating?
Rob

[Aircooled]

God I,m useless at this, it wouldn`t upload my pic but still uploaded the post There is a small black box next to the cover on the battery, it seems to me to be some kind of sensor? It is connected to a small rubber hose which is connected itself to the radiator rubber hose, whatever it is it`s broke(snapped) any ideas, please?
Rob

[Hell Razor5543]

Well, the first thing that would be useful to know is what the car is; model, variant and year.

[Old-Guy]

As a general comment, members could help themselves by adding details of their vehicle(s) to their signature.

[Aircooled]

OOOOPS gimme a break guys I,m new to all this, it`s an 03 model (52 plate) C5, 2.2 HDI

[Hell Razor5543]

Welcome aboard. Other than that, I cannot help as I have no knowledge of the C5 in any form, but it won't take long before somebody comes along with useful advice.

[addo]

It's a MAP sensor.

[Aircooled]

Thanks Addo, but erm, whats a MAP sensor? Anything to do with my aircon which is playing up? Will it cause any long term harm if I do nothing about it?

[Mandrake]

A MAP sensor is a "Manifold Absolute Pressure" sensor that measure the air pressure in the inlet manifold.

On a petrol engine its essential - the engine will run very poorly or not at all without it.

A normally aspirated diesel doesn't need a MAP sensor as there is no throttle butterfly to generate vacuum (thus it would always read atmospheric pressure) however on a turbo diesel it would be used to measure the boost pressure after the turbo, so I'm assuming the hose that its attached to is the intercooler air return hose not a water hose.

If the turbo waste gate is ECU controlled chances are you will loose a lot of power if the MAP sensor is not functioning, so definitely get it fixed.

[Aircooled]

Sorry I,ve not been on for a while, been busy with family affairs, thanks for the tips, I,ve come to the conclusion that I don`t need the sensor, I unplugged it for a day and noticed no loss of power or running problems. Cheers

[qprdude]

Hmm, strange. Perhaps you're used to lack of power and fixing the map sensor pipe would let you feel the difference.
If it was broken in the first place, you wouldn't notice any difference by disconnecting it.

[KevMayer]

My sensor broke off in exactly the same way.

You need to get a new sensor from a main dealer.

This sensor measures the turbo boost pressure and is essential for boost control.

[Aircooled]

Thanks guys, I suppose I,d better get a sensor aswell now, I didn`t even know it had a turbo, this could well be the final nail in my C5 coffin, I love the car, it drives like a dream, comfy, well appointed, good on fuel (ish lol) but along with the other problems I,m having I,m wondering is it all worth it (see my post, so many problems)

[waynedance]

It's worth it, I love my 2.2 runs like a dream but it does get pampered.

Good luck, hope all works out.

[Aircooled]

It's worth it, I love my 2.2 runs like a dream but it does get pampered.

Good luck, hope all works out.

Thanks mate, mine used to run like a dream, but not for long, I like the car, like it a lot but it seems there is so much computerised/technical/ECU/brainsearing complicated stuff on them, it makes liking them bloody hard! I probably bought a pig in poke