my 07 plate 19d multijet doblo with 20000 mls has had the engine management light on for two weeks,at first it lost power just now and again but today it realy lost it,i couldnt get up the slghtest hill and struggled along at 30mp on the flat,when i revved it up black smoke poured out plus some oil,its now in a garage mechanic mentioned it could be erg valve/turbo/diesel particular filter ,he said the filter costs £1100.00 is this right?find out tomorrow what the story is looking forward to that

Blank of the EGR valve and if power returns as it did on my 1.9 multi,bingo!

does sound like egr valve, either blank off or clean, or preferably both.
you should download fiatecuscan (free) and buy a vagcom cable off ebay to connect laptop up to car and read error.
this will also come in handy for deleting the error & getting rid of the management light