AGR Deactivation: Where to Find Setting?

Hello, where can I check if the AGR (Abgasrückführung) system has been deactivated via software? I want to find the cause of the malfunctioning AGR before I replace all my vacuum hoses. Where can I find the checksum(s) in the control unit? How can I identify incorrect checksums, and what can I conclude from a value of 'xy'? According to Audi Ingolstadt, my control unit is supposed to have incorrect checksums. My workshop told me this, and they checked it online and compared it to their values.

Thank you, Moby.

MWB 003, Field 2. If this field always contains the value 850, or a similar value, then the vehicle was likely decommissioned by the tax office.
Unfortunately, I don't know what it looks like when it's closed via the switch – I haven't bothered to look for it yet.

vwSchrauber wrote:

MWB 003, Field 2. If it always contains 850, or a similar value, then it was shut off via the KF. Unfortunately, I don't know what it looks like when it's closed via a switch - I haven't bothered to look for it yet.

Not always.

I will not provide more specific details about how to identify something, for various reasons. I believe that those individuals who are interested in identification should be able to find that information out on their own.

Best regards, Rainer.