Abstract: A method for evaluating signals of a sensor unit including at least two sensors. The method includes reading in a first sensor value of a first of the sensors and a second sensor value of a second sensor, the first and second sensor value each representing one parameter of a substance to be measured by the sensors or a linking of the parameters. A threshold value range is read in, which maps a range of combinations of at least the first and second sensor values, which represents the presence or a value of the substance to be measured in surroundings of the first and second sensors. A combination of the read-in first and second sensor values is recognized as being outside the threshold value range. The threshold value range is changed into a changed threshold value range so that the combination is situated within the changed threshold value range.