NO matter how many times i take my 2.2ctdi for a service this issue is never fixed! After a while my engine management light comes on limiting my revs to 2000 - sometimes even whilst driving and once on the mway. One garage said it was my air quality sensor and reset it. It goes off for a while after a service but always comes back. Its amazingly annoying and at times dangerous as you cant get up to speed. It'll cycle thru - engine management light on - limit to 200 revs /engine management light on - drives normal /engine management light off /no problem, then repeats ad infinitum till i get it serviced then its good for around 8000 miles before kicking off again - HELP!