The invention relates to a method for operating a device (16) for the dosed supply of a liquid, at least having at least one pump (1) for the delivery of the liquid, wherein the pump (1) has a pump housing (2) with at least one inlet (3) and at least one outlet (4), wherein an eccentric (5) is arranged on the pump housing (2) and wherein a deformable diaphragm (7) is arranged between the pump housing (2) and the eccentric (5), wherein the deformable diaphragm (7) and the pump housing (2) delimit at least one delivery path (8) from the at least one inlet (3) to the at least one outlet (4) and form at least one seal (9) of the delivery path (8), wherein, for the purposes of delivering the liquid, the at least one seal (9) can be displaced along the delivery path (8) by way of a movement of the eccentric (5). The pump further has at least one pressure sensor (10) which is connected to the outlet of the pump. According to the invention, a liquid is delivered by means of the pump (1) in step a) of the method. According to the invention, a time curve (12) of the pressure at the outlet (4) of the pump (1) is monitored during delivery by the at least one pressure sensor (10) in step b) of the method. According to the invention, an angle position (13) of the eccentric (5) of the pump (1) is detected using at least one characteristic feature (14, 15) of the time curve (12) at the outlet (4) in step c) of the method.