Filter element with a permanently attached sensor

having a filter element comprising a pleated filter medium (1), wherein the pleated filter medium (1) ends (2) and longitudinal sides (3), wherein the filter medium (1) folds (4) with fold valleys (5), folding walls (6) and having pleat tips (7), and wherein the filter medium (1), a sensor (8) is associated with a filter element of the type mentioned, in view of the task to design such and further, that the sensor used is always matched to the employed filter media, characterized in that the sensor (8) in such a way by tether (9) is connected to the filter element, that it can only be released by destroying the filter medium (1), the tether means (9) and / or the sensor (8) by the filter element.