" f " fault on dash
 

Can anyone have any information that can help me in the removal of the "f" fault code on the dash of my a170 cdi.
I've replaced the whole gear selector for one that's been tested as fully working. The car now drives fine but the "f" is still there. I've a fault code reader which I have tried but no faults are shown.

Can a normal garage remove it IR will I have to go to a Mercedes garage.