See also:

Clearing the shift range restriction
Pull and hold the right-hand steering wheel paddle shifter until D is shown again in the multifunction display. The automatic transmission shifts from the current shift range directly to D. ...

Mercedes-Benz M-Class Owners Manual
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On-board diagnostic interface
WARNING If you connect equipment to the on-board diagnostics interface, it can affect the operation of the vehicle systems. This can impair the operating safety of your vehicle while driving ...