Read out workshop code - AP00.20-P-0000-13V

Switch on ignition.
Press the system selection button (S110s3) repeatedly until the kilometer reading is shown in the upper multifunction display (A1p13).
Press the scroll forward/back button (S110s1) repeatedly until the service indicator appears in the upper multifunction display (A1p13).
Press the trip odometer reset button (A1s3) briefly 3 times until the "SERVICE MENU" is displayed in the upper multifunction display (A1p13).
Illustrated on model 171

Fig 1: Identifying Multifunction Display, System Selection Button And Forward/Back Button
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Press the + and - buttons, adjustment of specific functions and volume control (S111s1) repeatedly until menu item "SERVICE DATA" is highlighted.
Confirm selection with lower system selection button (S110s3).
The highlighting marks the multi-digit workshop code (1).
Note workshop code (1).
The workshop code (1) is needed for dynamic maintenance (ASSYST PLUS) in the WIS.
Press the upper system selection button (S110s3) repeatedly until the kilometer reading is displayed in the upper multifunction display (A1p13).
Switch off ignition.

Fig 2: Identifying Workshop Code
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.