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Exhaust & Emissions

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

How do I know if my catalytic converter has failed?

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.

How Coal Rollers Work

Coal rollers create plumes of black smoke by forcing more fuel into a diesel engine than it can handle. Learn about coal rolling at HowStuffWorks. See more »

How much air pollution comes from cars?

How much air pollution comes from cars? Keep reading to learn about air pollution and how much comes from cars. See more »

Here are seven easy ways to reduce your emissions without affecting the quality of your daily commute. Learn more about the top 7 ways to reduce your driving emissions without reducing quality of life. See more »

What can you do to reduce your car's emissions? Visit to learn how to reduce your car's emissions. See more »

Can we make tailpipes that capture CO2?

Tailpipes that capture CO2 would make a dent in humans' contributions to greenhouse gas emissions. Learn about tailpipes that capture CO2 and if they exist. See more »

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

How Mufflers Work

Mufflers cancel out most of an engine’s noise. Find out how mufflers cancel sound waves, why engines are so loud, and look inside a muffler to learn about backpressure. See more »

How Catalytic Converters Work

Catalytic converters are one of the most important parts of a car's emissions control system. Learn about catalytic converters and catalytic converter laws. See more »

How do I know if my catalytic converter has failed?

Catalytic converter failure can be hard to diagnose. Learn several possible causes for catalytic converter failure on this page. See more »

What is a catalytic converter and how does it work? See more »