Catalytic converter

имя существительное [автомобильное дело] каталитический дожигатель выхлопных газов

Большой англо-русский словарь

Catalytic converter

noun an automobile exhaust-system component containing a catalyst that causes conversion of harmful gases (as carbon monoxide and uncombusted hydrocarbons) into mostly harmless products (as water and carbon dioxide)

Merriam-Webster's Collegiate Dictionary