Car Parts Plus

Basics Of Your Vehicle’s Catalytic Converter

Your car’s engine produces exhaust gases as the result of its 4-stroke combustion process. The gases flow from the combustion chamber through each cylinder’s exhaust valve, and make their way toward your vehicle’s tailpipe. Along that path lies the catalytic converter. Its job is to prevent specific elements within the exhaust gas from emitting from the tailpipe. These elements include hydrocarbons (HC), carbon monoxide (CO), and nitrogen compounds (NOx).

Emission standards require that such pollutants are removed from the exhaust. As long as your cat converter is working properly, your car should have no problem passing your state’s emissions test. On the other hand, the cat can become clogged for a number of reasons. If that happens, you might experience a lack of engine power, lower fuel economy, and stalling.

In this article, I’ll describe how the catalytic converter works and explain the factors that can cause it to fail.

How The Component Works

If your engine is running cleanly (i.e. it is not burning oil), the exhaust coming from the combustion chamber should contain very few hydrocarbon and carbon monoxide emissions. In other words, the cat shouldn’t have much to do. Over time, the efficiency of your engine will decline. It will burn less cleanly and the level of HC and CO in the exhaust will rise.

Within your catalytic converter is a ceramic honeycomb. It is covered with special compounds that react to the presence of the exhaust. This reaction causes the molecules in the compounds to hold onto the hydrocarbons, carbon monoxide, and nitrogen compounds, thereby preventing their release into the atmosphere. In doing so, your cat is able to convert otherwise harmful emissions into near-harmless elements, such as nitrogen and carbon dioxide.

Reasons They Fail

The more pollutants that are present in the exhaust, the harder your catalytic converter needs to work. The harder it works, the hotter it becomes. The most common reason cat converters fail is because they become clogged and overheat. The underlying cause of the clog needs to be addressed in order to prevent a replacement cat from clogging.

For example, if your vehicle’s spark plugs become fouled, misfiring can occur. If the exhaust valve fails and causes a leak in a cylinder’s compression, unburned gas can pass into the exhaust system. If an oxygen sensor fails, causing the air-fuel mixture to be too rich, your cat can melt. This can cause an obstruction that leads to a backpressure problem. The result is a stalled engine.

Normally, this component begins operating between 400 and 600 degrees Fahrenheit. This is called its light off temperature. The temperature usually climbs to approximately 1,600 degrees. If the component is forced to work too hard, the temperature can climb to over 2,000 degrees, causing the ceramic honeycomb to weaken. Severe problems usually follow.

If you suspect the level of emissions coming from your engine is too high, have your mechanic check whether your catalytic converter needs to be replaced. Otherwise, you may experience costly engine problems down the road.

Used Car Parts

Subscribe to this Car Parts Plus feed

Other Interesting Car Articles

• A Closer Look At Your Vehicle’s Catalytic Converter (0)

A Closer Look At Your Vehicle’s Catalytic Converter

Given the job it performs, your car’s catalytic converter receives less attention than it deserves. Auto technicians agree that this relatively small component is one of the marvels of recent automotive technology. It converts the harmful pollutants that are produced within your vehicle’s engine into less harmful emissions. Like all auto parts, it can fail due to a number of factors. When it does, your engine will be less able to perform efficiently.

I’ll explain the basic operation of your catalytic converter and how it performs its job below. I’ll also describe the types of emissions it prevents your vehicle from releasing as well as common reasons the component can malfunction.

How The Component Works

Your engine produces exhaust gases as the result of its 4-stroke combustion process. Those gases contain a number of emissions that are considered harmful to people and the environment. Your catalytic converter sits underneath your car and functions as a crossing guard between your engine and tailpipe. The gases produced by your engine’s combustion process enter the cat.

Inside the component, there is a grid-like ceramic honeycomb. This honeycomb has been covered with special compounds that are activated when exhaust comes into the converter. The compounds adhere to the pollutants and prevent them from escaping through your tailpipe. They convert them into less harmful elements, such as carbon dioxide and nitrogen.

Types Of Emissions

There are three main pollutants that your catalytic converter is designed to capture and convert: carbon monoxide, hydrocarbons, and nitrogen compounds.

Carbon monoxide is produced due to imprecise combustion. Normally, the exhaust generated in your engine is largely comprised of carbon dioxide – or technically, carbon with two oxygen molecules. However, due to a lack of precision during combustion, the carbon molecules often bind with a single oxygen molecule. That results in carbon monoxide.

Hydrocarbons are generated by carbon and hydrogen molecules that are not burned. When they bind together, they become harmful to anyone who breathes them.

Nitrogen compounds result from the same process as hydrocarbons. They are unburned nitrogen molecules that bind to oxygen molecules. They contribute to smog.

Potential Causes Of Failure

Your catalytic converter relies heavily on your car’s oxygen sensors. If the sensors are working properly, the level of emissions within the gases that emerge from the combustion process will be manageable. If any of the sensors fail, the air-fuel mixture can be too lean or rich. That causes your engine to produce a higher volume of pollutants, which can lead to your cat overheating and melting.

Your cat can also fail to perform its job effectively if your vehicle is burning oil. Over time, that leads to contaminants and deposits accumulating within the component. A clog will become imminent.

If you suspect that your catalytic converter is failing, visit your dealership or a local repair garage. In the event that it is damaged, clogged, or contaminated, you’ll need to have it replaced.

Used Car Parts

Subscribe to this Car Parts Plus feed

Other Interesting Car Articles

• Your Car’s Gas Tank Draining Removing And Installing (0)
• When your Car is Overheated (0)
• When Your Car Fails The Emissions Test (0)
• What Your Car’s Tire Wear Is Telling You (0)
• What To Do When Your Tire “Blows Out” (0)