Pressure sensor and method for operating a pressure sensor

A pressure sensor (23) comprises at least one micromechanical sensor element (1) having at least one pressure-sensitive membrane (3) which covers a cavity (4) in a base material (2) and has a membrane electrode (5). A fixed counter electrode (6) is arranged inside the cavity (4) and, together with the membrane electrode (5), forms a first measuring capacitor (7) for measuring a first measuring pressure. A reference capacitor (10) is arranged inside the cavity (4) and comprises at least one first and one second fixed reference electrode (11, 12). The pressure sensor (23) is operable in at least one first operating mode in which the first measuring capacitor (7) and the first reference capacitor (10) are connected in a first bridge circuit. The pressure sensor (23) is operable in at least one second operating mode in which the membrane electrode (5), the counter electrode (6) and the reference electrodes (11, 12) are interconnected in such a way that the membrane electrode (5), together with the at least one fi