Car Exhaust and Emissions

This section can help you keep your exhaust system working properly. Learn how mufflers, catalytic converters and oxygen sensors work.

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Whether diesel- or gasoline-powered cars spit out more toxins depends on the pollutant measured, a new study says.

By Shelley Danzy

In a truck pull competition, excessive clouds of diesel smoke are a byproduct of the truck's functionality. But coal rollers have taken this idea from the county fair to the public roads -- all in the name of making people angry.

By Cherise Threewitt

You see it every time smoke billows from your car's exhaust pipe. There's no denying that vehicles are major contributors to air pollution. But how much are they responsible for?

By Linda C. Brinson & Francisco Guzman


To reduce your cars emissions, you can help its catalytic converter work more efficiently by preheating it, or you can inject a urea solution into your exhaust pipe. Learn what you can do to reduce your car's emissions in this article.

By Contributors

It seems like a logical answer to the climate crisis: capture the carbon dioxide that our cars emit. Is it that simple? And what do sand and silica have to do with it?

By Josh Clark

I have a dirt bike and the exhaust pipe has this big bulge in it near the engine. What is the bulge for?

Every car out there has a muffler -- it performs the crucial job of turning thousands of explosions per minute into a quiet purr. Mufflers use some cool technology to dim the roar of an engine. Learn the principles that make it work.

By Karim Nice


A catalytic converter is one of the most important parts of a car's emissions control system. It treats the exhaust before it leaves the car and removes a lot of the pollution. Learn how they work.

By Karim Nice, Charles W. Bryant & Sascha Bos

Exhaust emissions test check for the absence of a catalytic converter or a malfunctioning one during an emissions inspection. Read on to learn how you can find out if your catalytic converter has failed.

An oxygen sensor in a car is a very important part of making your engine run smoothly. Learn what it does and what can happen if your oxygen sensor fails.