Antipolution system failure

Thank you very much for your answer.
Yesterday looking at the engine found that the air duct that goes from the air filter to the admission was disconnected in the middle, that is to say that the air did not pass through the filter or the sensor (I suppose it is the one that measures the flow) that is at the exit of the filter. Connect that duct again and today after circulating about 30 km stopped and when the car turned back the witness light turned back to normal.
I take advantage of another consultation, which advise addictive for diesel to keep the injectors clean and improve combustion ????
YP ultradiesel diesel

Look most additives are enriched gasoline, try to throw a liter of gasoline, take the car to the road and take it for example in fourth to more than 4000 rpm or third the theme is surely that you have carbonilla (fuel without burn) in turbo, escape sensors or something similar.
If this does not go out to turn to the posts previously read

Hi Nferrecio, look I never advise additives to clean the injectors or any for gasoline, the best way to clean injectors is by ultra sound, it is not expensive and it is done every 25000 or 50000 thousand kilometers, the expense is not so much and the fuel save is noticeable, the additives generate contaminating particles and carbonas recurrences that are housed in the approaches of the valves. That is why I do not advise them,

I have suffered the same failure of the antipolution system in my 307. I know that this topic is already many years old and maybe you don't even remember it, but if you remember what the solution you found, I would appreciate it.