Hi all, I have a 1.2 16v 06 campus and ive noticed it has really bad acceleration it will barely do 15mph up a slight hill in 2nd my engine management light is on and i have been told it could be my exhaust valve (as my plugs have been changed)... ive been told it could cost over £500 to get it fixed, is this true? or has any1 else got any suggestions please?