i think is CLALDUV: Fehlerklasse: Schubumluftventil-Endstufe try and report
A couple of options.
1) Change the fault class like mentioned above so if diagnosis of N249 fails it does not throw DTC.
2) Change conditions needed to start diagnosis to unreachable values i.e DLDUVES, TMDLDUV, TMFDUV, TMMZUV
so diagnosis never starts.
These will help the malfunction DTC but not the open circuit DTC. Thus far I haven't found a way to prevent ECU from checking for open circuit. DTC can be surpressed BUT more than likely interfere with fuel trims adaptation.
Maybe something in DEKON function and ESKONF
