Hi to everybody.i am writting you from Greece.Does anyone knows what the egr valve does?when it is working?when this is close and when this is open?

anybody?

Exhaust Gas Recirculation valve.

Exhaust Gas Recirculation valve.

when this valve is working?

Intermittently; it's an emission control device. For more detail look here.

Intermittently; it's an emission control device. For more detail look here.

thank you for the link.another question.do you know how can i see with vag-com if thiw valve is working correctly?

No idea about using vag-com; an exhaust analyser giving an out of limits reading would be potentially diagnostic though.

If it isn't working (and everything else is !) you should get the yellow "engine" warning light illuminated.

Had mine replaced on this engine - cost around £100.