A method of operating a pressure transmitter and pressure transmitter

The invention relates to a method of operating a pressure transducer and a pressure transducer with a pressure sensor (23) of a flexible measuring diaphragm (2) and a base body (3), between which a cavity (20) with a reference pressure is included. By a control and evaluation device (25) is determined in a pressure measurement mode, the capacitance of a first capacitor as a measuring capacitor with two electrodes (21, 22) and a second capacitor as a reference capacitor disposed in the edge region of electrodes (22, 24) and a function of which measured value of the medium pressure (P) is calculated. In a diagnostic mode, the diagnostic capacity of a capacitor is evaluated by the electrode (21) of the measuring capacitor and, disposed on the same surface electrode (24) of the reference capacitor is formed and determined. This is largely independent of the respective medium pressure (P) and of the self-adjusting bending line of the measuring diaphragm (2) in an advantageous manner. Use of the diagnostic capacitor changes in relative humidity in the cavity (20) and / or through a crack (32) penetrating the process medium (33) can be detected. Thus, a warning signal can be generated and printed on a service unit in time for a pending failure.