Method for validating the angular position of the rotor of an electrical machine for a motor vehicle provided with a means for measuring the components of the angular position of the rotor, an on-board control unit and a means for calculating the angular position, in which an excitation signal of the means for measuring the components of the angular position of the rotor is generated by the means for calculating the angular position and retrieved by the on-board control unit in a non-synchronised manner with the internal clock of the control unit, the means for measuring the components of the angular position of the rotor being capable of supplying signals proportional to the sine and the cosine of the angular position of the rotor, the angular position of the rotor is determined in accordance with the components of the angular position of the rotor and the excitation signal via the on-board control unit and the calculation means at a second time, following a first time, the method being characterised in that it comprises the following steps: the angular position of the rotor is determined via the means for calculating the angular position at the first time, the angular position of the rotor is determined via the on-board control unit at the second time, in a state synchronised with the excitation signal, the time elapsed between the determination of the angular position of the rotor via the means for calculating the angular position at the first time and a measurement of the components of the angular position of the rotor by the on-board control unit at the second time is determined, the value of the angular position which would have been determined by the means for calculating the angular position at the second time is estimated, in a state synchronised with the excitation signal, in accordance with the time elapsed, the rotation speed of the electric machine and the value of the angular position of the rotor determined via the means for calculating the angular position at the first time, it is determined whether the deviation between the estimated value of the angular position which would have been determined by the means for calculating the angular position at the second time and the angular position of the rotor determined via the on-board control unit at the second time is less than a predetermined threshold, if this is the case, it is considered that the angular position is valid, if not it is considered that the angular position is invalid. the angular position of the rotor is determined via the means for calculating the angular position at the first time, the angular position of the rotor is determined via the on-board control unit at the second time, in a state synchronised with the excitation signal, the time elapsed between the determination of the angular position of the rotor via the means for calculating the angular position at the first time and a measurement of the components of the angular position of the rotor by the on-board control unit at the second time is determined, the value of the angular position which would have been determined by the means for calculating the angular position at the second time is estimated, in a state synchronised with the excitation signal, in accordance with the time elapsed, the rotation speed of the electric machine and the value of the angular position of the rotor determined via the means for calculating the angular position at the first time, it is determined whether the deviation between the estimated value of the angular position which would have been determined by the means for calculating the angular position at the second time and the angular position of the rotor determined via the on-board control unit at the second time is less than a predetermined threshold, if this is the case, it is considered that the angular position is valid, if not it is considered that the angular position is invalid.