A method for detecting a faulty measurement (M, m k) of at least one extensive electric quantity of an electric network (1;1') comprising an upstream supply and at least two downstream outlets (4 i; 4 i h), the supply and the outlets being each provided with a sensor (6, 8 i; 6 h, 8 i h) for measuring the extensive electric quantity, each sensor conducting, in a synchronous way with the other sensors, a measurement of the extensive electric quantity depending on a parameter p, the parameter p being: - either the time t, each value of the parameter p being a time instant t j, - or one or several harmonics which make up a measurement the method comprising at least N measurements of the value on the upstream supply and on each downstream outlet (4 i) conducted for different values of the parameter p, the method being characterized in that once the measurements have been made: a) the relationship between the measurements is formalized, for each value of the parameter p with the equation: M p j = ∑ i = 1 N a i m i p j wherein j is an index of the parameter p, M(p j) is a measurement of the sensor (6; 6 h) of the upstream supply for a value p j of the parameter, N is the number of downstream outlets (4 i), i is the downstream outlet initial index varying from 1 to N, m i (p j) is a measurement from the sensor (8 i; 8 i h) of the downstream outlet (4 i) of index i for the value p j of the parameter and a i is a gain of this measurement; b) a system of N equations and N unknowns is generated, the unknowns being the gains a i; c) the system of equations is solved, by calculating each gain a i; d) the gains a i are controlled and: - if all the gains (a i) are equal to 1, it is considered that no sensor (6, 8 i; 6 h, 8 i h) has conducted a faulty measurement; - if at least one (a k) of the gains a i is different from 1, it is considered that at least one sensor has conducted a faulty measurement (M, m k). - either the time t, each value of the parameter p being a time instant t j, - or one or several harmonics which make up a measurement the method comprising at least N measurements of the value on the upstream supply and on each downstream outlet (4 i) conducted for different values of the parameter p, the method being characterized in that once the measurements have been made: a) the relationship between the measurements is formalized, for each value of the parameter p with the equation: M p j = ∑ i = 1 N a i m i p j wherein j is an index of the parameter p, M(p j) is a measurement of the sensor (6; 6 h) of the upstream supply for a value p j of the parameter, N is the number of downstream outlets (4 i), i is the downstream outlet initial index varying from 1 to N, m i (p j) is a measurement from the sensor (8 i; 8 i h) of the downstream outlet (4 i) of index i for the value p j of the parameter and a i is a gain of this measurement; b) a system of N equations and N unknowns is generated, the unknowns being the gains a i; c) the system of equations is solved, by calculating each gain a i; d) the gains a i are controlled and: - if all the gains (a i) are equal to 1, it is considered that no sensor (6, 8 i; 6 h, 8 i h) has conducted a faulty measurement; - if at least one (a k) of the gains a i is different from 1, it is considered that at least one sensor has conducted a faulty measurement (M, m k). a) the relationship between the measurements is formalized, for each value of the parameter p with the equation: M p j = ∑ i = 1 N a i m i p j wherein j is an index of the parameter p, M(p j) is a measurement of the sensor (6; 6 h) of the upstream supply for a value p j of the parameter, N is the number of downstream outlets (4 i), i is the downstream outlet initial index varying from 1 to N, m i (p j) is a measurement from the sensor (8 i; 8 i h) of the downstream outlet (4 i) of index i for the value p j of the parameter and a i is a gain of this measurement; b) a system of N equations and N unknowns is generated, the unknowns being the gains a i; c) the system of equations is solved, by calculating each gain a i; d) the gains a i are controlled and: - if all the gains (a i) are equal to 1, it is considered that no sensor (6, 8 i; 6 h, 8 i h) has conducted a faulty measurement; - if at least one (a k) of the gains a i is different from 1, it is considered that at least one sensor has conducted a faulty measurement (M, m k). - if all the gains (a i) are equal to 1, it is considered that no sensor (6, 8 i; 6 h, 8 i h) has conducted a faulty measurement; - if at least one (a k) of the gains a i is different from 1, it is considered that at least one sensor has conducted a faulty measurement (M, m k).