The Car-Owners Guide to Buying Catalytic Converters & Parts

Views 1 Like Comments Comment
Like if this guide is helpful
The Car-Owner's Definitive Guide to Buying Catalytic Converters and Parts

The catalytic converter is an important component on modern automobiles. This vital addition to a vehicle exhaust system was a response to growing public concern over carbon monoxide, hydrocarbons, and other toxic emissions associated with internal combustion engines. Although cars are by no means the only source of environmental pollution, catalytic converters help ensure that vehicle emissions are responsible for as little of the damage as possible. For this reason, many governments mandate that all vehicles have a properly installed and functioning catalytic converter.

Car owners typically install new catalytic converters for one of two reasons: failures and theft. In many cases, a failure is caused by engine issues, electrical issues, or issues related to neighbouring exhaust components. Theft is also an issue, as catalytic converters are a valuable source of scrap metal. If it is time to replace a malfunctioning or missing catalytic converter, buyers may want to begin with an understanding of how this important component works. A system in itself, knowledge of the various parts within it can help buyers better determine the cause of failure. Buyers familiar with the types and brands of catalytic converters have an easier time locating the correct catalytic converter when it is time to purchase one.

How Catalytic Converters Work

The standard modern vehicle is equipped with a three-way catalytic converter, a component that performs three different functions. The first function of a catalytic converter is to reduce the volume of nitrous oxide produced by the engine and convert it into less harmful chemicals such as oxygen and nitrogen. The second function is an oxidation process that converts toxic carbon monoxide into carbon dioxide. In the third and primary function of a catalytic converter is to transform unburned hydrocarbons into water and carbon dioxide. The catalytic converter performs each of these critical functions before the vehicle emits any chemicals from the exhaust system.

Catalytic Converter Parts

Although they are part of the larger exhaust system, catalytic converters are essentially systems themselves. Modern catalytic converter systems contain a core, also known as a honeycomb, which is typically made from either stainless steel or ceramic. The core enables the catalyst to perform the oxidation process used to convert toxic emissions into less harmful chemicals. Within this core is the catalyst, made of palladium, platinum, or rhodium. Which metal comprises the catalyst plays a key role in the oxidation process. The catalyst enables the catalytic converter to reduce and convert toxic gases into something much safer.

The washcoat is another vital element of a catalytic converter. Added directly to the core, this component is a balanced combination of aluminium and silicon that creates a hard, rugged surface. The washcoat strengthens the exterior of the core and enhances the overall efficiency of the converter.

Why Catalytic Converters Fail

Unlike other complex engine systems, catalytic converters do not contain any moving parts. They are simple devices that function passively. However, there are several factors that attribute to failure, to include rust, clogs, contamination and the failure of external support components


Rust is a threat to numerous exterior vehicle components, but exhaust components are more vulnerable than others. This problem is compounded in humid climates or regions in close proximity to the ocean. Unfortunately, the buildup of rust on exhaust parts is inevitable, and sooner or later, most catalytic converters fall victim to it.

Engine Buildup

In some instances, an engine runs with more fuel than it is able to handle. This condition is known in the automotive world as "running rich". It causes unused fuel to accumulate and burn within the catalytic converter. If this happens, the core of the unit is easily damaged by the fierce temperatures boiling inside.


Many catalytic converter failures are the direct result of contamination. Contamination is caused by either fuel or oil entering the unit. A blown head gasket is one of the most common causes of contamination.

Failed Parts

There are numerous other parts that directly impact the proper functioning of the catalytic converter. When these parts fail, it leads to failure of the catalytic converter as well. In addition to head gaskets, these parts include O2 sensors, spark plugs, and spark plug wires. Typically, the failure of these components is indicated by automatic activation of the check engine light. If diagnosed and addressed quickly, the issue can be resolved before the converter is damaged.

As the heart of the system, the core is the most important component of a catalytic converter. While some parts can be repaired, complete or partial failure of the core usually means the entire unit needs to be replaced.                          

Types of Catalytic Converters

When it comes to buying catalytic converters, buyers should shop for parts according to the make, model, and year of their vehicle to ensure a correct fit. Buyers can purchase the item from their vehicle manufacturer, or purchase an aftermarket replacement. Aftermarket replacement parts are made by a number of different manufacturers and many of these items are labelled universal, meaning one part is designed to fit several different makes or models.

Find Catalytic Converters by Make, Model, and Year

Catalytic converters sit at the back end of a vehicle's exhaust system. They come in a variety of sizes and styles according to the vehicle they fit. Owners replacing a catalytic converter need to know the make, model and year of manufacture for their vehicle in order to find the right part.

Shop for OEM or Aftermarket Catalytic Converters

Many owners prefer original equipment manufacturer (OEM) parts over aftermarket parts. OEM parts often fit better, and are easier to install. Aftermarket parts are popular with owners for the simple fact that the converters on many older cars have been discontinued and are, therefore, difficult to find. Because many are less restrictive than OEM components, quality aftermarket catalytic converters can deliver a higher flow, resulting in increased torque and horsepower.

Shop for Catalytic Converters by Brand

Aftermarket catalytic converters are made by a number of different manufacturers. Brands like Klarius, known for its line of emission control products, manufacture a large number of aftermarket catalytic converters. Bosal and BM Catalysts are other reputable makers of universal aftermarket parts. Many of these universal components offer a straightforward installation process that accommodates most vehicles.

Buying Catalytic Converters and Parts on eBay

Consumers can find significant cost savings and a large inventory of catalytic converters and parts when they shop with internet retailers. For example, eBay carries a vast selection of catalytic converters and other parts from hundreds of different sellers. eBay carries a variety of aftermarket components, as well as original parts made by car manufacturers such as Volvo, Citroen, and Renault.

Searching for Catalytic Converters and Parts on eBay

In addition to a wide range of parts to choose from, eBay offers shoppers a user-friendly search process. There is a search box on each page, so buyers can easily look for needed items from anywhere on the site. When ready, buyers can simply type in the name of the item they are searching for into the search box. For example, typing in "Mitsubishi catalytic converters" returns a page chock full of listings containing items relevant to that search.

Another option is to use the "Search Parts & Accessories" feature. Found on the eBay Motors portal, this feature lets buyers look for items by matching the part in question against the make and model of a car.

Narrowing Search Results

From here, it is easy to narrow a search even further with the Advanced Search feature. Advanced Search gives shoppers access to a variety of different filters, including price range, buying format, and location. Shopping by location allows buyers to search for items within a certain country or region or limit search results to a specified distance from a postcode.


Catalytic converters are important vehicle exhaust components. They convert harmful engine emissions, such as hydrocarbons, carbon monoxide, and nitrogen oxides into less harmful compounds. Many governments mandate the installation of catalytic converters on all vehicles in an attempt to reduce the level of vehicle emissions polluting the atmosphere.

Replacing a catalytic converter is a simple process for buyers who go into it equipped with some basic knowledge. Shoppers need to consider the make and model of vehicle when purchasing a catalytic converter. There are a number of different aftermarket brands to select from, or shoppers can purchase parts manufactured by the company that made the car. Before replacing a faulty catalytic converter, buyers should troubleshoot the engine and exhaust system to ensure there are no other underlying causes for the failure.

Due to government regulations and emissions testing, replacing a catalytic converter and related parts is not something that can be put off. Driving a vehicle with a faulty catalytic converter is damaging to the vehicle and the environment. Shoppers who go into it armed with a basic knowledge of how catalytic converters work, why they fail, and how to select the right one, find purchasing one an easy task.

Have something to share, create your own guide... Write a guide
Explore more guides