An injection-molded plastic sealing cap having a tubular cap body with a longitudinal axis, which cap body transitions integrally into a plate that extends at least predominantly in a radial direction, in which the inner circumference of the tubular cap body has at least one holding projection that protrudes radially inward into the inner space that is circumferentially encompassed by the cap body, wherein the plate has a window that is associated with the at least one holding projection and is aligned with the holding projection with which it is associated, viewed in the direction of the longitudinal axis of the sealing cap.