Thank you, is this after removal as the ERG valve appears to be buried under the inlet manifold which is wedged under the front bulkhead. My Haynes manual is not clear on its removal do you have any suggestions?

I found a pic of it and wow... if it's back against the firewall, or front bulkhead, I wouldn't be surprised if you have to drop the engine to pull it. How do you know it's dirty or broken?
You need to research a mechanic that has experience with Citroen and fair prices.

Thank you for your reply. I was hoping that I wouldn't have to got to such extremes as droping the engine to get it out.
All that I know is that the car is kicking out a lot of black sooty smoke and I have change the filters and injectors. This was one thing that i was told could be a cause therefore i was going to check it out but needed some advice.

What error codes are in the computer?
A faulty oxygen sensor could make it run rich.
So could other stuff like a mass flow sensor if if has one.
Fix this before the rich mixture damages the catalytic converter and cost you lots of money