Abstract: A filter for a control flow of a fuel injector, wherein a primary fuel flow enters the injector through an inlet aperture, and wherein part of the primary fuel flow forms a secondary fuel flow which enters a control valve through a control flow aperture, wherein the filter is located such that only the secondary flow of fuel passes through the filter, the filter includes filter orifices such as slots, holes or perforations, wherein at least one dimension of the filter orifices is less than the nozzle control valve lift value.