70MCE

Hi everyone, Need a help of solving my problem with a 7 speed S-Tronic Gearbox. My car is 2014 A6 C7 3.0TDi 245bhp CDUD, transmission code PXD. Car has 158k miles on the clock. Have been changing gearbox oil and filters every 15k miles, recently (2k miles ago) have changed Flywheel, Complete Clutch Unit all brand new. After changing flywheel & clutch the noise did not disappeared (maybe it got somewhat quieter) still have grinding noise when it shifts from 2nd to 1st gear. Bought a mechatronic repair kit 0B5398048D and replaced old parts with new ones. Unfortunately nothing changed same grinding noise. P.S All other gears are shifting perfectly hardly noticeable when it change gears up or down with no jerking when shifting from P to D or Revers gear. P.S.S Other day was sitting in the car scanning for a fault codes (non found) engine was running when I did a scan and when I pressed brake pedal got the grinding noise similar to the one mentioned above. Car was in park with a running engine this never happen before. Maybe someone had same issue and knows what is the problem and knows how to fix it? Appreciate your help