The invention relates to a human-machine interface for a telediagnosis system. The data conversion, the data completion, the data preparation and the computation of a diagnosis result ensue in a central diagnosis center provided in the form of a call center. The computed diagnosis result is displayed in completed form on a display screen whereby enabling a selected assistant in the call center to view the result. The communications expense for the telediagnosis can be considerably reduced, in particular, by the data completion being performed first in the central diagnosis center. As a result, the exchange of complete text files is unnecessary. This enables, in particular, the use of the SMS standard from the mobile radio telephone industry. An error message is conveyed from the technical system to be diagnosed, particularly from the vehicle to be diagnosed, by means of an SMS message. This SMS message is evaluated by a diagnostic program, and a first diagnosis result is computed. This first diagnosis result is automatically converted into an XML structure by the human-machine interface, and is supplemented with additional data concerning the vehicle or from the vehicle according to further evaluation of the first diagnosis result. The data completion automatically ensues once triggered by the original SMS. This diagnosis result supplemented in such a manner and the prepared diagnosis result are displayed on a display screen whereby enabling the assistant in the call center to view the result. This relieves the burden placed upon the assistant of many routine requests for additional information.