For control unit access, a vehicle to be checked is identified using an identifier. Control and/or monitoring operations covered by the control unit access are selected. A communication link is set up over a selected vehicle communication interface. Communication devices covered by the selected vehicle communication interface are ascertained. Independent control and/or monitoring operations covered by the control unit access are ascertained, where these operations are associated with available communication means and are not dependent on a superordinate control and/or monitoring operation. A control and/or monitoring operation, which has the greatest number of subordinate dependent control and/or monitoring operations, is selected for execution.