In a method of operating a telematics system, the presence or absence of an unauthorized access to a motor vehicle is determined by a control unit integrated in the motor vehicle. When determining the presence of an unauthorized access to the vehicle a functional unit, integrated in the motor vehicle and configured to operate an engine start of the vehicle and/or to unlock or lock the motor vehicle, is irreversibly deactivated by the control unit in response to the unauthorized access to the motor vehicle, and specified data about the unauthorized access is sent by the control unit to a vehicle-remote server of the telematics system.