Have a 2004 Citroen C5 1.6 HDI, there is an orane engine management light on in the dash, also the display says "depolluiton system faulty" and "Risk of Paticle filter blocked", can you please help with a fix for these???

sounds like a rheostat problem..

What is a 55 plate?

Is there any fault indication on the dash where the radio display is.
Anti pollution is basically citroens way of saying emissions system so it could be as simple as a loose emissions pipe but from what you say and the car does not run it could be your catalytic converter (part of the exhaust system) has failed causing the engine management system to cut in and protect the engine.
If there is no fault apart from anti pollution showing in the radio display find someone with a diagnostic machine to give you a better idea of the fault. Hope this helps a bit.

Take it to a citroen agent. the 2004 and 2005 had faulty turbos and thats the fault. Citroen parts are the same but cheaper.

engine bay in bulk head or passenger footwell

Anti pollution light, I never heard of a Check engine light being called that.
Read on please.

Hello
When the service engine soon light (Also called the check engine light or engine management light) is turned on this is to alert you to the fact that Powertrain Control Module (computer) has detected a failure somewhere in the systems it controls you may not feel any difference in the way the engine runs, this can be the transmission or the engine or emission system, there are fault codes set in the modules memory for these faults. What needs to happen now is to have the powertrain control module scanned with a special tool called an OBD2 electronic engine control scanner or a OBD2 code reader. Once the code(s) are read then you must perform the diagnostics for each code and make the appropriate repairs based on the findings of the diagnosis that was performed, this is called doing "Pinpoint" testing.

Don't worry I'm sure you will get the solution of your problem, just check the link I attached
citroen

Hi mate
In is possable you have a faulty coolant temp sensor.
This could be confirmed by having a diagnosis check done at a garage.
It might have 2 sensors fitted so if it needs them make sure you replace the right one