Method for controlling a hydraulically operated power screwdriver comprising a lever that can be pivoted by a piston-cylinder unit, comprising a ratchet arrangement for a step-by-step rotation of a ratchet bushing by advancing strokes and return strokes, and a drive unit with a motor-driven pump for tightening a screw connection; comprising the steps of: - entering a setpoint torque or a setpoint pretensioning force or the screw size, the grade of material, the thread pitch and the clamping length into an electronic input unit, - determining by an electronic evaluation unit a setpoint pressure to be generated by the pump and corresponding to the setpoint torque or the setpoint pretensioning force or the screw size, the grade of material, the thread pitch and the clamping length, - pressure loading of the piston-cylinder unit for performing the advancing stroke until the setpoint pressure is reached and immediately switching to a return stroke upon reaching the setpoint pressure by pressure relief and spring pressure or by activating pressure loading of the piston-cylinder unit to perform a return stroke, - measuring the time from the beginning of the pressure loading until the setpoint pressure is reached or until the initial pressure after pressure relief is reached, - repeating the pressure loading and pressure relief and measuring the time until the setpoint pressure or the initial pressure is reached, - comparing the measured time intervals and switching off the pressure loading cycles if at least the last measured time interval is shorter than at least the penultimate measured time interval, characterized in that after establishing a first short time interval, two further pressure loading actions are carried out, an average value is calculated or a sum is calculated from these three short time intervals and from three longer time intervals measured prior to the three short intervals and the repeated pressure-loading cycles are switched off if the average value or the sum of the short time intervals is smaller than the average value or the sum of the longer time intervals. - entering a setpoint torque or a setpoint pretensioning force or the screw size, the grade of material, the thread pitch and the clamping length into an electronic input unit, - determining by an electronic evaluation unit a setpoint pressure to be generated by the pump and corresponding to the setpoint torque or the setpoint pretensioning force or the screw size, the grade of material, the thread pitch and the clamping length, - pressure loading of the piston-cylinder unit for performing the advancing stroke until the setpoint pressure is reached and immediately switching to a return stroke upon reaching the setpoint pressure by pressure relief and spring pressure or by activating pressure loading of the piston-cylinder unit to perform a return stroke, - measuring the time from the beginning of the pressure loading until the setpoint pressure is reached or until the initial pressure after pressure relief is reached, - repeating the pressure loading and pressure relief and measuring the time until the setpoint pressure or the initial pressure is reached, - comparing the measured time intervals and switching off the pressure loading cycles if at least the last measured time interval is shorter than at least the penultimate measured time interval,