In the case of a method of communicating between a motor vehicle and a diagnostic unit, a wireless communication connection is established between the motor vehicle and the diagnostic unit after an authorization of the diagnostic unit has been checked. The diagnostic unit is connected with a vehicle key assigned to the motor vehicle, and the authorization of the diagnostic unit is checked by use of authorization data stored in the vehicle key. A diagnostic unit for implementing such a method has devices for connecting with a vehicle key assigned to the motor vehicle. The diagnostic unit is suitable for receiving authorization data from the vehicle key, for the indirect or direct wireless communication with the motor vehicle, and for proving its authorization with respect to the motor vehicle by way of the received authorization data.