skoda fabia 1.4 mpi emissions porblem

i have brought a a skoda fabia 1.4 8v mpi engine but it failed mot on emissions ive done diagnostics and is said emissions power control valve and mas air flow sensor but skoda say i don't have mas air flow sensor i am gonna replace power control valve weekend but i dont think it will change anything as valve just burns the gasses in the fuel tank all the other sensors are working but co2 is really high and some other does any one have any ideas