Skip the auto shop - Our mechanics make house calls

Q: How Does a Catalytic Converter Work?

asked by on

How does a catalytic converter work?

A catalytic converter is a device used to reduce the emissions of an automotive engine. Not enough oxygen is available to oxidize the carbon fuel in these engines completely into carbon dioxide and water; thus toxic by-products are produced. Catalytic converters are used in exhaust systems to provide a site for the chemical reaction of oxidation and the reduction of toxic by-products.

A catalytic converter uses basic chemical reactions to reduce the pollutants a car makes. It converts around 98% of the harmful fumes produced by a car engine into less harmful gases. It is composed of a metal housing with a ceramic honeycomb-like interior with insulating layers. This honeycomb interior has thin wall channels that are coated with a layer of aluminum oxide. This coating is porous and increases the surface area, allowing more reactions to take place and containing precious metals such as platinum, rhodium, and palladium. The construction requiring these precious metals is the cause of the consistent reports of recent catalytic converter thefts.

The fuel-injection system introduces the sensors needed to maintain the control of the exhaust environment within the converter required for a proper chemical reaction. This control system comprises oxygen sensors that monitor how much oxygen is in the exhaust stream, and in turn tells the engine computer to adjust the air-to-fuel ratio, keeping the catalytic converter running at the stoichiometric point (14:1 air-to-fuel) required and near 100% efficiency.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: I cant find specific laws on modifying vehicles.

The law states that all vehicles have to pass a state inspection for sound, lights, and safety. The following is the laws to follow when changing the items you have mentioned. ______________________________________________ Laws for exhaust The exhaust must be equipped...

Q: Weird sound and shaking as well as lower gas mileage and poor acceleration

It sounds like you may have a clogged catalytic converter. As you may already know, the catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When this is clogged, this...

Q: When accelerating, the sound is different

Hi there. Heavy black smoke is usually a sign of a rich fuel condition present in your car's engine. When this happens, the motor is receiving more fuel than it can otherwise burn during the regular combustion cycle. This excess...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...