A gas measuring system, having a measurement sensor (1) which records an exhaust gas from an internal combustion engine and has an outer electrode (6), which is exposed to the exhaust gas to be measured, a first measuring cell (4), a second measuring cell (8) that is connected to the first measuring cell (4), and in which a measuring electrode (10) is arranged, and a reference electrode (11) that is exposed to the ambient air. The measuring cells (4, 8) are located in a solid electrolyte (2), and all the electrodes (10, 11) are in contact with the solid electrolyte. A circuit which in a first pump flow (Ip0) pumps oxygen ions between the first measuring cell (4) and the outer electrode (6), in a second pump flow (Ip1) pumps oxygen ions between the second measuring cell (8) and the outer electrode (6), and in a third pump flow (Ip2) pumps oxygen ions between the measuring electrode (10) and the outer electrode (6), and which comprises a control unit (C) which records Nernst voltages between the measuring cells (4, 8) and a reference electrode (11).