Catalytic converters are one of your car's most important exhaust system parts — they help reduce the vehicle's environmental impact, so it meets emissions standards. Though catalytic converters last about 10 years, various factors can impact their life span, so a replacement may be necessary more frequently.

Car owners have many factors to consider when choosing the right catalytic converter. Understand which option in the market is the best choice to help your car run efficiently for years.

Understanding the Role of a Catalytic Converter

A catalytic converter is located between the engine and muffler to clean the exhaust gas from the engine. It removes pollutants such as carbon dioxide, nitric oxide and nitrogen dioxide with a heat-resistant honeycomb-shaped ceramic interior that has hundreds of cells layered with precious metals like palladium, platinum and rhodium. These precious metals clean the exhaust gas by separating or changing the molecules into safer elements like oxygen.

Catalytic converters help reduce the impact of emissions on the environment and human health. Since the Clean Air Act of 1970, cars in the United States must have a catalytic converter to meet emissions regulations.

Types of Catalytic Converters

Various types exist to help car manufacturers and owners meet emissions regulations. The most common include:

Two-Way Converters

A two-way or oxidation catalytic converter oxidizes carbon monoxide to create carbon dioxide and hydrocarbons. This converter also oxidizes unburned hydrocarbons into carbon dioxide and water. The exhaust gasses go into the substrate and have a chemical reaction with the precious metals. These converters operate efficiently with a lean fuel mixture.

Since two-way converters only have an oxidation catalyst, they cannot oxidize nitrogen. For this reason, car manufacturers began phasing out two-way catalytic converters in gasoline engines in 1981. However, these converters are still used for diesel engines because they work best at reducing sulfur emissions.

Three-Way Converters

The three-way catalytic converter has oxidation and reduction catalysts to control nitric oxide and nitrogen dioxide emissions. It has three uses:

  • Reduce nitrogen oxide to oxygen and nitrogen using rhodium
  • Oxidize carbon monoxide to carbon dioxide using palladium and platinum
  • Oxidize unburned hydrocarbons to water and carbon dioxide using palladium and platinum

These converters are paired with OBD-II diagnostic systems to alert drivers to catalytic converter performance problems.

This type was designed to replace the two-way converter and help vehicles meet strict emission standards. Today, the three-way catalytic converter is the most common in gas-powered cars.

Three-Way Plus Air Converters

The three-way plus air catalytic converter has the same uses as three-way converters, with the addition of an air pump and tube supply. Reducing nitrogen oxide is most effective when minimal oxygen is present. Once the nitrogen oxide is removed from the exhaust gas, the air pump adds more oxygen to the mixture before the carbon monoxide and hydrocarbons are oxidized. This converter presents efficiency concerns and has been phased out since the 1980s.

Factors to Consider When Choosing a Catalytic Converter

Catalytic converters are specific to certain vehicles, so car owners need to make sure they buy the right part. Installing an incompatible converter can lead to poor performance or extensive exhaust system and engine damage.

The catalytic converter you need depends on several factors, such as:

  • Vehicle make and model: Catalytic converters are unique to every car as technology improves from one car model to the next. The specifications and dimensions of a converter can change between different models of a make or versions of the same car.
  • Vehicle weight: Catalytic converters have a gross vehicle weight rating (GVWR) measurement. The label on your driver's side door pillar should have your car's GVWR. Choose a catalytic converter with a GVWR that is the same or higher than your car's.
  • Engine size: The size of the catalytic converter you need depends on your engine size. Catalytic converters correspond to the engine size to work correctly. Choose a converter rated for your engine size. For universal converters, your vehicle can have the same engine size or smaller than the converter is rated for.
  • Emission standards: Catalytic converters need to follow federal emissions standards. Car owners who registered their vehicles in California, Colorado, New York or Maine have state-specific regulations to comply with, too.
  • Additional features: Some catalytic converters have features like oxygen sensors and secondary air injection systems. If your car needs these features, choose a converter with them and vice versa.

How to Select a Catalytic Converter for Your Car

Follow these steps when buying your catalytic converter:

  1. Select your car specifications: Find converters compatible with your car's year, make and model. StockWise Auto has a vehicle selection tool to narrow the options and display only the catalytic converters compatible with your car.
  2. Identify your emission standards: Your car may have a Vehicle Emissions Control Information Tag with your vehicle's factory OBD-II emissions certification. You can locate this sticker in the engine compartment. Find a catalytic converter that is compliant with this certification and state-specific standards that apply to you.
  3. Determine the catalytic converter configuration: Catalytic converters are direct-fit or universal-fit. Direct-fit offers a fitment like the OEM part. A universal-fit converter is compatible with many cars but may require cutting, fabrication or welding for the most secure fit.

Buy a Catalytic Converter From StockWise Auto Today

Knowing how to choose the right catalytic converter is important for car owners. A converter designed for your car will filter harmful emissions to protect the environment. StockWise Auto has the replacement catalytic converter your car needs to operate efficiently.

We are a replacement car part manufacturer with a wide selection of catalytic converters in stock at the best price online. Our inventory includes top brands like DormanWalker and AP Exhaust, so you can be confident in your purchase. Plus, our professional and friendly team is available to assist you if you need help choosing the best catalytic converter for your vehicle. Browse our options and place your order today, or contact us to learn more about specific listings.