A blow-by treatment assembly (10) for a vehicle having an engine (22) emitting blow-by gas (18) includes a duct (16) for receiving blow-by gas from the engine. A catalyst trap (14) is disposed in fluid communication with the duct (16). The catalyst trap (14) removes hydrocarbon emissions from the blow-by gas (18). A pump (12) pumps the blow-by gas (18) through the catalyst trap (14). An outlet (32) is in fluid communication with the catalyst trap (14) for emitting the blow-by gas to either the ambient or to a tailpipe.