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

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: Exhaust manifold

You may have broken bolts or studs in the engine head that would cause an exhaust leak. You may need to remove the manifold and extract the broken off bolts from the cylinder head by drilling them out and using...

Q: Cat monitor will not run, even though i've done the 55 mph for 5 minutes or more numerous times....

If the cat monitor will not finish and pass after multiple tries then you may have a weak sensor or a catalyst that is bad. I'd suggest having the vehicle scanned to test the O2 sensors for slow or limited...

Q: A.I.R. pump is missing in my car

Hello. The A.I.R. system is an emissions system that is designed to inject air into the exhaust manifold to help with the combustion of any unburned fuel before it reaches the catalytic converter, resulting in cleaner emissions. In order to...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...