All engines must have one, it reduces Carbon Monoxide in the atmosphere and this is how. The catalytic converter is a compartment in the engine that contains oxygen. This is how the reaction occurs, Carbon Monoxide is 1 Part Carbon and One part Oxygen, while Carbon Dioxide is one part Carbon and 2 parts oxygen. When the Carbon Monoxide passes through the catalytic Converter it is oxidised meaning that Another oxygen atom will be added to it, causing The Carbon monoxide to have one part Carbon and Two atoms of oxygen, therefore turning the Carbon Monoxide into Carbon Dioxie. I will Tell You a Secret though, Most of the Carbon Monoxide pollution in the world doesn't come from cars. It comes From Tree leaves when they go through a process called 'Leaf Necrosis' which is when leaves turn from Green to yellow and get dry and crumple up, they release Carbon Monoxide during this process.
[Edited by Summy® - 7/22/2002 10:07:47 PM]