Method for determining multiplicative faults of a sensor installed in a system comprising a plurality of sensors, comprising the steps of: - detecting an effective target signal (s) from a target sensor, representative of a target quantity of the system; - detecting one or more auxiliary signals respectively from one or more auxiliary sensors of the system besides the target sensor, representative of auxiliary quantities of the system; - determining an estimated target signal (s*) representative of the target quantity from the one or more auxiliary signals; characterized in that the method further comprises: - determining a first quadratic difference (r+) between the effective target signal (s) multiplied by a multiplicative positive factor (c+) greater than 1, and the estimated target signal (s*); - determining a second quadratic difference (r) between the effective target signal (s) and estimated target signal (s*); - determining a third quadratic difference (r-) between the effective target signal (s) multiplied by a positive multiplicative factor (c-) smaller than 1, and the estimated target signal (s*); - determining a first ratio (r/r+) between the second (r) and first quadratic differences (r+); - determining a second ratio (r/r-) between the second (r) and third quadratic differences (r-); - comparing the first (r/r+) and second ratios (r/r-) with a first comparison factor (Kf); - determining the square of the effective target signal (s); - determining the square of the estimated target signal (s*); - comparing the square of the effective target signal (s) and square of estimated target signal (s*) with a second comparison factor (Ke); - establishing the presence of multiplicative faults of target sensor if at least one between the first (r/r+) and second ratios (r/r-) is greater than the first comparison factor (Kf), and at least one between the square of the effective target signal (s) and square of the estimated target signal (s*) is greater than said second comparison factor (Ke). - detecting an effective target signal (s) from a target sensor, representative of a target quantity of the system; - detecting one or more auxiliary signals respectively from one or more auxiliary sensors of the system besides the target sensor, representative of auxiliary quantities of the system; - determining an estimated target signal (s*) representative of the target quantity from the one or more auxiliary signals; - determining a first quadratic difference (r+) between the effective target signal (s) multiplied by a multiplicative positive factor (c+) greater than 1, and the estimated target signal (s*); - determining a second quadratic difference (r) between the effective target signal (s) and estimated target signal (s*); - determining a third quadratic difference (r-) between the effective target signal (s) multiplied by a positive multiplicative factor (c-) smaller than 1, and the estimated target signal (s*); - determining a first ratio (r/r+) between the second (r) and first quadratic differences (r+); - determining a second ratio (r/r-) between the second (r) and third quadratic differences (r-); - comparing the first (r/r+) and second ratios (r/r-) with a first comparison factor (Kf); - determining the square of the effective target signal (s); - determining the square of the estimated target signal (s*); - comparing the square of the effective target signal (s) and square of estimated target signal (s*) with a second comparison factor (Ke); - establishing the presence of multiplicative faults of target sensor if at least one between the first (r/r+) and second ratios (r/r-) is greater than the first comparison factor (Kf), and at least one between the square of the effective target signal (s) and square of the estimated target signal (s*) is greater than said second comparison factor (Ke).