An air intake plenum (100) disposed in an air induction channel (112) in a hood (116) defined by a bottom channel wall (120), a rear hood reinforcement wall (122), a cab wall (124), and an exterior skin (126), where the air induction channel extends between an air inlet (114) laying in a plane generally parallel with the direction of travel “T” of the vehicle to an air outlet (118), includes a plenum inlet (128). The plenum inlet (128) is generally co-planar with the air inlet (114) of the air induction channel (112). At least one side wall (136, 138) extends from the plenum inlet (128) to a plenum outlet (144) and is angled downwards towards the bottom channel wall (120). Air through the plenum inlet (128) impinges against the side wall (136, 138), exits the plenum outlet (144), and is directed to impinge against the bottom channel wall (120) of the air induction channel (112) where contaminants drop out of the air.