A method for controlling an operating condition of a vehicle including executing, at each of operating cycles, at least one diagnostic phase applied to at least one computer controlling an operating condition of the vehicle, during which the computer produces and consumes data, at least one of the data capable of taking a particular predetermined value resulting from detection of an operating failure by the computer, so as to indicate a diagnostic result associated with the failure. The method stores, at the end of each cycle, the particular value for the failure concerned and initializes the diagnostic phase at the beginning of the next operating cycle with the stored particular data so as to reproduce, for the failure concerned, the diagnostic result supplied by the diagnostic phase when it was last executed.