An ambulatory infusion device including a pump drive unit, a valve drive unit and a control unit. The pump drive unit includes a pump actuator and a pump driver coupled to a piston of a metering pump unit. The valve drive unit includes a valve actuator and a valve driver coupled to a valve unit for transmitting a valve switching force or torque. The control unit controls a repeated execution of: (a) placing the valve unit in a filling state； (b) displacing the piston in a retraction direction； (c) displacing the piston in an advancing direction by a backlash compensation distance； (d) switching the valve unit from the filling state into a draining state； and (e) further displacing the piston in the advancing direction in a number of incremental steps over an extended time period.
