Method for checking a printing head for applying a fixing agent in an ink printing device

For testing a Fixiermitteldruckkopfes on nozzle failures, a reference mark is printed by the nozzles of a color ink print head and a check mark by overprinting of the color ink from the nozzles of the color ink print head and a fixing agent from the nozzles of Fixiermitteldruckkopfs to a printing substrate. The check mark and the reference mark are compared. If the reference mark and the test mark at least partially correspond to one another, this indicates that the nozzles of the Fixiermitteldruckkopfs operate erroneously, that is fail completely or eject the fixing under a too large angular deviation.