A method for operating a floor cleaning machine (i), the floor cleaning machine (i) having a cleaning fluid container, a dirty liquid container, and a chassis for moving the floor cleaning machine over a floor surface to be cleaned, the floor cleaning machine having a cleaning device with cleaning elements which are designed to engage with the floor surface to be cleaned, the cleaning device being connected to the cleaning fluid container for supplying cleaning fluid to the cleaning device and being designed to apply cleaning fluid to the floor surface to be cleaned, the floor cleaning machine having a dirty liquid receiving device which is connected to the dirty liquid container for discharging dirty liquid from the dirty liquid receiving device to the latter and being designed to receive dirty liquid from the floor surface to be cleaned, the method comprising the following steps: - moving the floor cleaning machine over a floor surface to be cleaned, characterized in that the method comprises the following further steps: - detecting the amount of cleaning fluid supplied from the cleaning fluid tank to the cleaning device during movement within a first time interval, - detecting the amount of dirty liquid which is discharged from the dirty liquid receiving device to the dirty liquid container during the movement within a second time interval, - comparing the detected amount of cleaning fluid with a first threshold value, - comparing the detected amount of dirty liquid with a second threshold value, - outputting a first error signal if the detected amount of cleaning fluid is greater than the first threshold and the detected amount of dirty liquid is less than the second threshold. the floor cleaning machine having a cleaning device with cleaning elements which are designed to engage with the floor surface to be cleaned, the cleaning device being connected to the cleaning fluid container for supplying cleaning fluid to the cleaning device and being designed to apply cleaning fluid to the floor surface to be cleaned, the floor cleaning machine having a dirty liquid receiving device which is connected to the dirty liquid container for discharging dirty liquid from the dirty liquid receiving device to the latter and being designed to receive dirty liquid from the floor surface to be cleaned, the method comprising the following steps: - moving the floor cleaning machine over a floor surface to be cleaned, - moving the floor cleaning machine over a floor surface to be cleaned, characterized in that the method comprises the following further steps: - detecting the amount of cleaning fluid supplied from the cleaning fluid tank to the cleaning device during movement within a first time interval, - detecting the amount of dirty liquid which is discharged from the dirty liquid receiving device to the dirty liquid container during the movement within a second time interval, - comparing the detected amount of cleaning fluid with a first threshold value, - comparing the detected amount of dirty liquid with a second threshold value, - outputting a first error signal if the detected amount of cleaning fluid is greater than the first threshold and the detected amount of dirty liquid is less than the second threshold. - detecting the amount of cleaning fluid supplied from the cleaning fluid tank to the cleaning device during movement within a first time interval, - detecting the amount of dirty liquid which is discharged from the dirty liquid receiving device to the dirty liquid container during the movement within a second time interval, - comparing the detected amount of cleaning fluid with a first threshold value, - comparing the detected amount of dirty liquid with a second threshold value, - outputting a first error signal if the detected amount of cleaning fluid is greater than the first threshold and the detected amount of dirty liquid is less than the second threshold.