A method for diagnosing a fault in the control of a three-phase electric motor current-mode controlled by a control signal. The method makes it possible to calculate the actual dead time present in each of the three control signals at a given time on the basis of compensated temporal offsets for each phase of the motor, of a predetermined measurement error common to the three phases of the motor and of a value of a amplitude of the current flowing through the transistors of the three pairs of transistors at the given time so as to detect a fault in the control of the motor when the absolute value of the calculated difference is higher than a predetermined detection threshold.