Computer-implemented method for determining the cause of a fault in an electrical circuit, comprising the following process steps: a) inputting (S1) of a graph-based circuit diagram simulation model (SM) of the electrical circuit, wherein, in the graph-based circuit diagram simulation model, electrical connection points of circuit components are modelled as graph vertices and electrical connections are modelled as graph edges , b) simulation (S2) of a fault in the electrical circuit by means of the graph-based circuit diagram simulation model, wherein - one graph edge in the graph-based circuit diagram simulation model is added or removed, - resulting connected components, and respective potential values and/or phase values of the graph vertices of the resulting connected components, are determined by reference to the modified graph-based circuit diagram simulation model, - and wherein, on the basis of the potential values and/or phase values of the graph vertices thus determined, the switching behavior of the electrical circuit is represented by the further addition and/or removal of at least one further graph edge, c) outputting (S3) of resulting potential and/or phase values for specified graph vertices in the form of simulated output signals, d) comparison (S4) of the simulated output signals with reference output signals supplied for the electrical circuit, and e) outputting (S5) of the cause of the fault corresponding to said fault, if the simulated output signals coincide with the reference output signals. a) inputting (S1) of a graph-based circuit diagram simulation model (SM) of the electrical circuit, wherein, in the graph-based circuit diagram simulation model, electrical connection points of circuit components are modelled as graph vertices and electrical connections are modelled as graph edges , b) simulation (S2) of a fault in the electrical circuit by means of the graph-based circuit diagram simulation model, wherein - one graph edge in the graph-based circuit diagram simulation model is added or removed, - resulting connected components, and respective potential values and/or phase values of the graph vertices of the resulting connected components, are determined by reference to the modified graph-based circuit diagram simulation model, - and wherein, on the basis of the potential values and/or phase values of the graph vertices thus determined, the switching behavior of the electrical circuit is represented by the further addition and/or removal of at least one further graph edge, - one graph edge in the graph-based circuit diagram simulation model is added or removed, - resulting connected components, and respective potential values and/or phase values of the graph vertices of the resulting connected components, are determined by reference to the modified graph-based circuit diagram simulation model, - and wherein, on the basis of the potential values and/or phase values of the graph vertices thus determined, the switching behavior of the electrical circuit is represented by the further addition and/or removal of at least one further graph edge, c) outputting (S3) of resulting potential and/or phase values for specified graph vertices in the form of simulated output signals, d) comparison (S4) of the simulated output signals with reference output signals supplied for the electrical circuit, and e) outputting (S5) of the cause of the fault corresponding to said fault, if the simulated output signals coincide with the reference output signals. <EOS>