Abstract: A computer-assisted diagnostic device for electronically controlled systems, which are arranged in an overall system, and a diagnostic process which can be implemented by means of a computer are provided. The diagnostic device and process are suitable for electronically controlled systems in a motor vehicle. Computers of a second type pertaining to the diagnostic device can at any time exchange by way of networks based on Internet technology current data and programs with a computer of a first type. The frequently changed and adapted diagnostic programs must only be filed on the computer of the first type, which considerably reduces the establishment and maintenance expenditures for the diagnostic programs and completely eliminates the program distribution expenditures. In the computers of the second type, dynamically loadable libraries are filed.