when the egr is turned off in a tuned file,how does it work? I mean,does the ecu take into account the airflow from maf and egr? I had a gander & didnt see how the ecu knows how the egr is blocked/blanked or unplugged. When i had my golf egr could be blanked & no codes would show.how does e39 know its interfered with so to speak? thanks

Depends People do it different ways

Some cars u can max a EGR map that's enough some u just have to do switch some u do both other you have a hysterics map and so on.