a linear exhaust - gas probe has a measuring cell for measuring a gas concentration in a measuring chamber by determining a measuring - cell voltage , and a pump cell for pumping gas by way of a pump current . a circuit configuration for operating the prove has a comparator circuit for comparing the measuring - cell voltage with a measuring - cell setpoint voltage and for providing a corresponding analog deviation signal . a pump current source provides the pump current . the source is controlled by the deviation signal using a control circuit for the approximation of the measuring cell voltage to the measuring cell setpoint voltage . in order to reliably limit the pump voltage with no significant detrimental effect on the operation , the circuit configuration further has a second comparator circuit for comparing the pump voltage with a predefined threshold voltage and for providing a corresponding binary switching signal ; and a counter coupling path between the output of the pump current source and the control circuit . the path is enabled when the voltage threshold is crossed .