The present invention relates to a conveyor dishwasher—with at least one final rinse zone with at least one final rinse nozzle for spraying final rinse liquid onto washware, and wherein a metering device associated with the final rinse zone is provided for adding a disinfectant to the final rinse liquid in a metered manner. A sensor device is configured to detect the concentration of disinfectant in the final rinse liquid which is sprayed in the final rinse zone. Furthermore, a control device is configured to compare the value of the concentration of disinfectant which is detected by the sensor device with predefinable concentration values and, in the event of excessively high deviations of the concentration of disinfectant from the predefinable concentration values, to interrupt the dishwashing process or to output a warning signal to an operator.