A test bench for a control system for controlling a wideband lambda sensor, which is configured to calculate an actual value, which represents an oxygen concentration in a measuring gap of a wideband lambda sensor or an indicator value from which the oxygen concentration can be derived, with consideration of a current generated by a pump voltage in an electrical circuit. In order to simulate the electrical response of a pump cell of the wideband lambda sensor, a first diode and a second diode are connected in parallel in the electrical circuit such that a current flows through the first diode at a first polarity of the pump voltage and a current flows through the second diode at a second polarity of the pump voltage.