why does diesel filter warning come up on my citroen c5 2002?

If its the diesel additive warning then the eolys fluid is low and needs topping up, don't go to Citroen though as they charge silly money!!
I went to peugoet and bought the eolys fluid from there, topped it up myself, the tank being behind the passenger side wheel lining, you will then need the computer resetting, all in all costs about 150 to 200 quid, citroen quoted me over a thosand pound when I had my C5

Chris King
February 2011