Method to operate a coriolis meter for determining a mass flow and/or a density of a medium flowing through a pipe that encompasses a coriolis meter, comprising: at least one measuring tube with an inlet (10.1) and an outlet (10.2), wherein the measuring tube is symmetrical relative to a plane of symmetry (10.3) running through a measuring tube cross-section; at least one vibration exciter for generating measuring tube vibrations, a first vibration sensor (12.1), a second vibration sensor (12.2), and a third vibration sensor (12.3), wherein the vibration sensors are configured to record measuring tube vibrations, wherein the vibration sensors are arranged at various points along a measuring tube center line (10.4), in particular in such a way that the first vibration sensor and the second vibration sensor are arranged symmetrically relative to the plane of symmetry, wherein the measuring tube forms a coriolis mode during mass flow with a vibration node in the area of the plane of symmetry, wherein the first vibration sensor is arranged on an inlet side of the measuring tube relative to the vibration node, wherein the second vibration sensor is arranged on an outlet side of the measuring tube relative to the vibration node, and wherein the third vibration sensor is arranged in the area of the vibration node, wherein the method encompasses the following process steps: measurement of a first measured variable using the measurement signals of the first vibration sensor and of the third vibration sensor, as well as measurement of a second measured variable using the measurement signals of the second vibration sensor and of the third vibration sensor, characterized in that the method encompasses the following further process steps: determination of a damping of the measuring tube vibrations, determination of an influence of the damping on the first measured variable, as well as on the second measured variable, formation of differences in measured values of the first measured variable and measured values of the second measured variable, so that an influence of the mass flow on the differences is canceled out, check for correspondence between the difference and the damping. at least one measuring tube with an inlet (10.1) and an outlet (10.2), wherein the measuring tube is symmetrical relative to a plane of symmetry (10.3) running through a measuring tube cross-section; at least one vibration exciter for generating measuring tube vibrations, a first vibration sensor (12.1), a second vibration sensor (12.2), and a third vibration sensor (12.3), wherein the vibration sensors are configured to record measuring tube vibrations, wherein the vibration sensors are arranged at various points along a measuring tube center line (10.4), in particular in such a way that the first vibration sensor and the second vibration sensor are arranged symmetrically relative to the plane of symmetry, wherein the measuring tube forms a coriolis mode during mass flow with a vibration node in the area of the plane of symmetry, wherein the first vibration sensor is arranged on an inlet side of the measuring tube relative to the vibration node, wherein the second vibration sensor is arranged on an outlet side of the measuring tube relative to the vibration node, and wherein the third vibration sensor is arranged in the area of the vibration node, wherein the method encompasses the following process steps: measurement of a first measured variable using the measurement signals of the first vibration sensor and of the third vibration sensor, as well as measurement of a second measured variable using the measurement signals of the second vibration sensor and of the third vibration sensor, characterized in that the method encompasses the following further process steps: determination of a damping of the measuring tube vibrations, determination of an influence of the damping on the first measured variable, as well as on the second measured variable, formation of differences in measured values of the first measured variable and measured values of the second measured variable, so that an influence of the mass flow on the differences is canceled out, check for correspondence between the difference and the damping. measurement of a first measured variable using the measurement signals of the first vibration sensor and of the third vibration sensor, as well as measurement of a second measured variable using the measurement signals of the second vibration sensor and of the third vibration sensor, characterized in that the method encompasses the following further process steps: determination of a damping of the measuring tube vibrations, determination of an influence of the damping on the first measured variable, as well as on the second measured variable, formation of differences in measured values of the first measured variable and measured values of the second measured variable, so that an influence of the mass flow on the differences is canceled out, check for correspondence between the difference and the damping. determination of a damping of the measuring tube vibrations, determination of an influence of the damping on the first measured variable, as well as on the second measured variable, formation of differences in measured values of the first measured variable and measured values of the second measured variable, so that an influence of the mass flow on the differences is canceled out, check for correspondence between the difference and the damping.