Method for operating a valve comprising at least one valve seat (15, 16), a valve plunger and a stepper motor for moving the valve plunger with respect to the or each valve seat (15, 16), namely for moving the valve plunger from a first position into a second position in which the valve plunger is pressed against a valve seat (15, 16) and for compressing a flexible element assigned to the valve plunger in said second position, whereby the stepper motor is driven in such a way that the stepper motor provides a defined number of steps (N TOTAL) in order to move the valve plunger from the first position into the second position and in order to compress the flexible element thereby providing tightness between the valve plunger and the valve seat (15, 16), whereby the stepper motor is driven in such a way that for a first number of steps (N 1) of said defined number of steps (N TOTAL) the stepper motor is operated at a first current level (I 1), wherein the first electrical current level (I 1) is determined in such a way that the stepper motor force at the first electrical current is higher than forces acting against the valve plunger movement in the first position; for a subsequent second number (N 2) of steps of said defined number of steps (N TOTAL) the stepper motor is operated at a second current level (I 2) being lower than the first current level; and for a subsequent third number of steps (N 3) of said defined number of steps (N TOTAL) the stepper motor is operated at a third current (I 3) level being higher than the second current level (I 2), wherein the third electrical current level (I 3) is determined in such a way that the stepper motor force at the third electrical current is higher than forces acting against the valve plunger movement in the second position, characterised in that the second electrical current level is determined in such a way that the stepper motor force at the second electrical current is higher than forces acting against the valve plunger movement in a transition position of the valve plunger between said first position and said second position. for a first number of steps (N 1) of said defined number of steps (N TOTAL) the stepper motor is operated at a first current level (I 1), wherein the first electrical current level (I 1) is determined in such a way that the stepper motor force at the first electrical current is higher than forces acting against the valve plunger movement in the first position; for a subsequent second number (N 2) of steps of said defined number of steps (N TOTAL) the stepper motor is operated at a second current level (I 2) being lower than the first current level; and for a subsequent third number of steps (N 3) of said defined number of steps (N TOTAL) the stepper motor is operated at a third current (I 3) level being higher than the second current level (I 2), wherein the third electrical current level (I 3) is determined in such a way that the stepper motor force at the third electrical current is higher than forces acting against the valve plunger movement in the second position, characterised in that the second electrical current level is determined in such a way that the stepper motor force at the second electrical current is higher than forces acting against the valve plunger movement in a transition position of the valve plunger between said first position and said second position.