1. Directly plug V4.94 Digiprog III Digiprog3 Odometer Master Programmer socket.Turn on the device. Enter password (Default power-on password is 1). Check the mileage on the dashboard
2. Select “PKW/LKW” at the digiprog3 Main Menu.
3. Then select vehicle model: MERCEDES.
4. Choose the detailed Benz model: W204 C-Class.
5. Select “TACHO DIAG” option.
6. The Digiprog 3 mileage correction tool will prompt which adapter should you plug in, here the device asks to plug ST16 adapter.
7. Next DigiProg 3 will ask you to manually enter the mileage displayed on the dashboard. Follow the system instruction.
8. The digiprog 3 is building communication with the vehicle. The new correct mileage will displayed on the dashboard.
9. Last step, exit the Digiprog 3 device and disconnect it with vehicle.
http://www.mileageprogrammer.com/adjust-mileage-on-w204-with-diprog-iii-v4-94/