206 1.4 engine mangement light problems

[Richard05]

i have a 2002 206 1.4 hdi with 92000 mls for a month or two the engine management light comes on sometimes straight from start up or when already running and sometimes limp mode is activated when this happens it sticks at 3000revs and it just picks away again fine no smoke or anything engine is a little noisy when below a certain rev range but does not use any oil could this be a egr valve problem or turbo problem have already fitted a new fuel filter also when turning on the ignition it shows the milage , service miles then 000000max with a picture of oil or water Also I think the cat or downpipe may be past its best

PLEASE HELP