periodically under normal engine operation the oil level l would drop slowly due to the loss or burning of engine oil in the internal combustion engine 12 if the measured oil level l continues to decline there should not be any significant diesel fuel leakage therefore it should be appropriate to reset all of the references l o k o and u03b7 o in steps 50 52 54 respectively as mentioned previously the oil sensor 18 may have a level output that could have a plus or minus 3 error therefore the fact that the oil level l is less than the reference for the oil level l o does not necessarily mean the oil level 14 in the oil pan 16 is actually less than the reference l o in order to prevent this uncertainty an alternative embodiment to step 48 in fig5 is graphically represented in fig6 the alternative method for resetting the references is generally indicated at 64 the method begins by identifying a number n that will indicate the number of iterations in which the measurements for the oil level 14 are taken a first oil level measurement l n is taken and measured to determine whether it is less than the reference oil level l o this step occurs at 66 the iterative oil level measurement l n is stored at 68 the counter n is increased by 1 at 70 it is then determined whether n has reached a limit x at 72 if not the alternative method 64 is released and the measurement method 30 is continued if the counter has reached its limit x and if at 74 one half of the iterative oil level measurements l n are less than the reference level l o the reference level.