the data measured are then stored in step s 4 the engine rpm is measured in step s 5 and in step s 6 compared to a prescribed value here 1000 min u2212 3 as long as the engine speed has not yet reached this prescribed speed the prm continues to be measured in step s 5 if the engine rpm has exceeded the prescribed limit rpm step s 7 examines whether the measured oscillator circuit frequency f osz is greater than a pre set frequency f lim the pre set frequency f lim is stored during production of the working device at the factory at the time the sensor is calibrated the frequency f lim corresponds to the oscillating frequency for the minimum oil level required if the frequency measured f osz is greater than f lim an led is turned on in step s 8 for operational controls and in step s 9 the oil level monitoring system is turned off the oil amount in the internal combustion engine is no longer monitored during the operating cycle only when the engine is restarted u2014 after it has been turned off u2014 does the oil level check begin again with step s 1 if it is determined in step s 7 that the frequency f osz measured is less.