Ok. I understand.
I actually fixed the EGR cooler to work now. It was disabled (isolated) since when I bought the car one and half year ago. I had great economy back then with EGR disabled.
Maybe something else is the reason, but now my consumption is higher and with the fixed EGR cooler now...
My Golf MkV BMM was making hissing noises. It was leaking exhaust gasses from well know spot:
The mechanic isolated the whole EGR cooler by putting a metal cap around point 15 and 16:
With this manipulation I was getting error P0401 Insufficient flow. (naturally)
After some time...