Selective Catalytic Reduction: Venting

The passive reservoir is equipped with on operating vent (2 in the 335d) and one filler vent. The operating vent is directed into the atmosphere. A so-called sintered filter tablet ensures that no impurities can enter the reservoir via the operating vent. This sintered tablet consists of a porous material and serves as a filter that allows particles only up to a certain size to pass through. The filler vent is directed into the filler pipe and therefore no filter is required.