Method of diagnosing the state of signal-forming chains of a detector including an array of detection bolometers, each chain comprising a bolometer, a circuit of stimulation, and a circuit forming a signal according to said stimulation, including forming an image of a substantially uniform scene on the array; applying at least first and second stimulations to the chains; reading the formed signals; and for each chain in a predetermined set, defining a neighborhood of chains; calculating coefficients of a polynomial interpolating the values of signals formed by said chain; calculating, for each chain of the neighborhood, coefficients of a polynomial interpolating the values of signals formed by said neighborhood chain; calculating an average and standard deviation of said coefficients of the neighborhood chains or of the set of neighborhood chains and said chain; and diagnosing if said chain is defective using the coefficients and the calculated average and standard deviation.