What is a Catalytic Converter?
'What is a catalytic converter?' is question many do not know and ask. A catalytic converter, or cat, looks like a rather large muffler that sits at the base of the exhaust manifold. The exhaust from each cylinder powers into the manifold and then into the converter, which contains hundreds of platinum-coated balls. Since it is a catalyst that enables a reaction, but doesn't take part itself, the cat continues to turn oxides of nitrogen, CO and hydrocarbons into water. Those gases it misses are recirculated through it, via an exhaust gas recirculation system. The exhaust is pretty well cleaned up by the time it exits the cat, and when it exits the tailpipe, you have little more than water and carbon dioxide, plus some trace elements.
For more info, see How to Repair a Catalytic Converter at Home