Simplify the following text for a Grade 12 native English-speaking person.
Original: A catalytic converter works by using a catalyst to stimulate a chemical reaction in which the by-products of combustion are converted to produce less harmful and\/or inert substances , such as the very poisonous carbon monoxide to carbon dioxide .
Simplified: It works by using a catalyst - usually Rhodium . The catalytic converter converts carbon monoxide into carbon dioxide .