Vortex flowmeter for measuring a flow rate of a fluid passing through a pipeline of the flowing medium comprising: a measuring tube for guiding the medium with a measuring tube wall and a measuring tube lumen formed by a measuring tube wall, wherein the measuring tube wall has an opening; a bluff body arranged in the measuring tube; a sensor device which is adapted to detect flow vortices caused by the damming body, wherein the sensor device comprises a paddle, a sensor base body and a piezoelectric element, wherein the sensor base body is arranged in the opening and seals with the measuring tube wall in a media-tight manner, wherein the paddle projects into the measuring tube lumen and is adapted to be moved from flow vortices from a force-free rest position, wherein the piezo element is arranged on a rear side (32.1) of the sensor base body facing away from the measuring tube and is adapted to detect deformations of the sensor base body caused by deflections of the paddle and to convert them into an electrical measuring signal; an electronic operating circuit which is adapted to detect and evaluate the measurement signal by means of an evaluation circuit and to provide flow measurement values, wherein the electronic operating circuit has a measuring circuit comprising an operational amplifier with an inverting input (51.1), a non-inverting input (51.2) and an output (51.3) as well as a first capacitor (52.1), wherein the first capacitor (52.1) forms a feedback between the output and the inverting input (51.1) or the non-inverting input (51.2), the respective input being a measurement input, wherein the respective other input (51.1, 51.2) is a reference input and a first reference voltage can be applied to it, and wherein the output is connected to an evaluation circuit of the electronic operating circuit, wherein the piezo element is connected on a side facing away from the operational amplifier with a second reference voltage, which in particular is equal to the first reference voltage, wherein the measuring circuit has a first switch (53.1), wherein the electronic operating circuit is adapted to connect the piezo element via the first switch (53.1) to the measurement input of the operational amplifier by means of a first switch position (53.11) and to charge it with a first charging voltage by means of a second switch position (53.12), wherein the electronic operating circuit is adapted by means of the evaluation circuit to derive from a discharging process of the piezo element information regarding a state of the piezo element and/or of an electrical connection of the piezo element to the electronic operating circuit and/or a mechanical connection to the sensor base body. a measuring tube for guiding the medium with a measuring tube wall and a measuring tube lumen formed by a measuring tube wall, wherein the measuring tube wall has an opening; a bluff body arranged in the measuring tube; a sensor device which is adapted to detect flow vortices caused by the damming body, wherein the sensor device comprises a paddle, a sensor base body and a piezoelectric element, wherein the sensor base body is arranged in the opening and seals with the measuring tube wall in a media-tight manner, wherein the paddle projects into the measuring tube lumen and is adapted to be moved from flow vortices from a force-free rest position, wherein the piezo element is arranged on a rear side (32.1) of the sensor base body facing away from the measuring tube and is adapted to detect deformations of the sensor base body caused by deflections of the paddle and to convert them into an electrical measuring signal; an electronic operating circuit which is adapted to detect and evaluate the measurement signal by means of an evaluation circuit and to provide flow measurement values, wherein the electronic operating circuit has a measuring circuit comprising an operational amplifier with an inverting input (51.1), a non-inverting input (51.2) and an output (51.3) as well as a first capacitor (52.1), wherein the first capacitor (52.1) forms a feedback between the output and the inverting input (51.1) or the non-inverting input (51.2), the respective input being a measurement input, wherein the respective other input (51.1, 51.2) is a reference input and a first reference voltage can be applied to it, and wherein the output is connected to an evaluation circuit of the electronic operating circuit, wherein the piezo element is connected on a side facing away from the operational amplifier with a second reference voltage, which in particular is equal to the first reference voltage, wherein the measuring circuit has a first switch (53.1), wherein the electronic operating circuit is adapted to connect the piezo element via the first switch (53.1) to the measurement input of the operational amplifier by means of a first switch position (53.11) and to charge it with a first charging voltage by means of a second switch position (53.12), wherein the electronic operating circuit is adapted by means of the evaluation circuit to derive from a discharging process of the piezo element information regarding a state of the piezo element and/or of an electrical connection of the piezo element to the electronic operating circuit and/or a mechanical connection to the sensor base body.