FAQ : How the Catalytic Converter Works

FAQ : How the Catalytic Converter Works


Catalytic converter devices are emissions control components for your vehicle that convert the exhaust fumes of combustion from your engine, and limit the amount of toxic emissions that are released from your tail pipe. Some of the emissions these converters are supposed to limit are carbon monoxide, hydrocarbons and nitrogen oxide, all of which are measured by way of a smog machine for some emissions restricted states.

The types of catalytic converter can vary depending on the type of usage or more specifically the type of pollutants  it’s meant to convert or filter. For most passenger vehicles the type of catalytic converter is usually a “three-way” converter, termed for the three separate types of pollutants it’s designed for.

Want to learn how catalytic converters work? This guide can help you  understand the fundamentals behind this emissions device. Have a check engine light or problem with your vehicle passing smog? Learn all about catalytic converters using this article and replace your emissions component today.

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How a catalytic converter works

What is a catalytic converter? – Simply put, the converter in your vehicle is a emissions control device. It’s there to limit the amount of toxic gasses and byproducts created by your combustion engine. There are many different types of catalytic converter, although most modern vehicles use what’s called a three-way converter.

Three way catalytic converters filter out three of the main pollutants generated by your combustion engine. The big three are carbon monoxide, unburned hydrocarbon and nitrogen oxide gasses.

When were catalytic converters first used? – Production vehicles in the 1975 model year first began to incorporate catalytic converter emissions devices. These were used to reduce emissions, through direct implementation from U.S. Environmental Protection Agency regulations.

The first catalytic converters were two-way units, unlike the three part ones found in modern vehicles today. These were used to reduce carbon monoxide (CO) and unburned hydrocarbons (HC).

Today they can be found on a variety of vehicles, as well as industrial equipment such as tractors and forklifts. Catalytic converters are usually implemented to conform to environmental guidelines or health and safety government regulations.

When do I need to replace my catalytic converter? – Typically when your catalytic converter fails, you’ll know it. Whether through a check engine light being turned on for catalytic converter failure, or excessive exhaust gases; catalytic converter failure is fairly obvious. One of the biggest clues is your check engine light turning on, indicating a problem with your vehicle.

How do I know if my catalytic converters legal? – If your vehicle is older than ten years old, you’ll need a OEM direct fit catalytic converter in order to pass smog. This is part of the new STAR smog system that requires a sniffer be connected to your tailpipe. If you are modifying your vehicle, check our guide here to find out whether or not your exhaust modifications are legal.

Why can’t I buy a used or aftermarket catalytic converter? – There has been recent changes to emissions laws, more specifically in California. Starting from 2009, the California Air Resources Board changed the way that catalytic converters are sold and purchased.

The changes to the CARB laws state that the converters must all clearly state a Executive Order or CARB EO number. This number will identify the vehicle that the converter is designed for, thereby confirming the legality of the part. Unfortunately many aftermarket catalytic converters do not have this CARB number identification, which make them illegal for purchase.