how do i get code(s)?

You will need an electronic scan tool to see what the codes are. Most Mercedes-Benz vehicles made after 1995 do not have the provision for "flash codes". In addition a basic, or off the shelf, electronic scan tool may not give you the information you need. If the code is set in another system, say the trans, a basic scan tool may only tell you that there is a code in the trans. Because of the complexity of the electrical system in newer Mercedes-Benz vehicles, I recommend having a dealership or M-B approved repair shop scan all systems in the vehicle. In some M-Bs there are over 30 different ECUs, most have at least 10.