No, the codes in the radio are for the radio.

All OBDC2 codes are accessed in every car via a connector under the dashboard by the steering column. It requires a reader. Any reader you can purchase will be "generic" and work on any brand car. Your Mercedes dealer and possibly a serious Mercedes independent mechanic will have a more sophisticated, very expensive reader that will show Mercedes-specific codes for things beyond the legal requirements as regards pollution compliance.

If the light isn't on, there's not much to worry about as regards codes. Of course, verify the bulb check that occurs during starting.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles