WHAT THE HECK IS A…Catalytic Converter?

To know what the heck a catalytic converter IS, we must first explore what the heck a catalytic converter IS NOT. A catalytic converter is not:

  1. An experimental tool only used at NASA
  2. A musical instrument that converts cat meows into beautiful melodies
  3. The thing that Doc Brown uses in the Back to The Future series to travel through time
  4. A type of religious foot apparel

Not that.

Not that.

So…what the heck is it, then?

A catalytic converter takes all the harmful pollution your vehicle creates, and makes it not-as-harmful before it is expelled out of the exhaust system.

Aww, yeah! Reducing pollution!

Aww, yeah! Reducing pollution!

How Does It Work?

I’m glad you asked. Chemistry is how it works. Your engine creates nitrogen, carbon dioxide, and water vapor as it uses fuel. It also creates some sneakier, more harmful emissions like carbon monoxide, nitrogen oxides, and hydrocarbons.  A catalytic converter consists of 2 catalysts: a reduction catalyst and an oxidation catalyst. A 3-way catalytic converter also has a control system.

Let’s hop on the Catalytic Converter train…

Choo choo!

Choo choo!






First Stop: Reduction Catalyst Junction

The reduction catalyst typically uses platinum and rhodium to help reduce the nitrogen oxide emissions. When an those nitrogen oxide molecules contact the catalyst, it removes the nitrogen atom from the molecule and holds on to it. That releases the oxygen from the molecules. The nitrogen atoms just bond with other nitrogen atoms that are also stuck to the catalyst.

Next Up: Oxidation Catalyst Junction

The oxidation catalyst typically uses platinum and palladium to reduce the unburned hydrocarbons and carbon monoxide by oxidizing (burning) them. This catalyst aids the reaction of the carbon monoxide and hydrocarbons with the remaining oxygen in the exhaust gas.

Final Stop: Control System Station

The control system monitors the exhaust stream, and uses this information to control the fuel injection system. An oxygen sensor tells the engine computer how much oxygen is in the exhaust. The engine computer can then adjust the air-to-fuel ratio, which measures the amount of oxygen in the exhaust gas. There has to be enough oxygen in the exhaust gas for the oxidization catalyst to burn the unburned hydrocarbons and carbon monoxide.

Don't forget to tip your conductor.

Don’t forget to tip your conductor.

Common Problems

Catalytic converters usually last about 10 years or so, but there are some issues that can shorten that lifespan:

  • Overheating—Although it takes a lot of heat to make a catalytic converter work (especially in the oxidation catalyst), it can be damaged if it gets TOO hot. That could be caused by a bad spark plug, damaged oxygen sensor, or leaking exhaust valve.
  • Contamination—If you ever use leaded gas, it could potentially contaminate and destroy the catalysts.
  • External Damage—Since the catalytic converter is located underneath the vehicle, there is the potential that it will be damaged if you drive over a lot of debris or jump a curb.
  • Clogging (not the dance that originated in the Appalachian Mountains)—Things like leaking coolant or oil can clog the catalytic converter, restricting the flow of exhaust gas through it, which means less oxygen gets to the engine. That can turn into engine response time slowing down or failing completely.
  • Being Stolen—This can definitely shorten the lifespan of your catalytic converter. Because the catalysts have precious metals like palladium, platinum, rhodium, and sometimes gold, they can be mighty tempting to a thief that happens to have about a minute and is carrying a reciprocating saw.
saw sihlouette                                    thief

So, there you have it. Now you know what the heck a catalytic converter is NOT, what the heck it IS, and how the heck it works. Mother Earth loves catalytic converters. So should you!


Tell me what other automotive parts baffle you. I’ll tell you what the heck they are!


Written by Ben Scharff

Leave a Reply

Your email address will not be published. Required fields are marked *