What Does a Catalytic Converter Do?

You probably don’t think much about your vehicle’s catalytic converter – until something goes wrong. There’s a lot going on inside this rather simple-looking part. It’s played a key role in cleaner air and better emissions, but it’s been standard equipment for less than 50 years. How did catalytic converters end up on today’s autos? It’s a fascinating story, but you’ll also learn about your converter’s inner workings along with how to spot problems with your unit.

Why You Need a Catalytic Converter?

Catalytic converters do one important job – converting dangerous emissions into less harmful byproducts. The average converter consists of an oblong metal box with one intake port and one exhaust port. But inside the unit is where all the work takes place. There’s a honeycomb-shaped structure coated in two types of catalyst – one for reduction and another for oxidization. These catalysts handle some common types of pollutants:

  • Reduction catalysts convert nitrogen oxides into nitrogen and oxygen.
  • Oxidative catalysts break down carbon monoxide and hydrocarbons into CO2 and water vapor.

Before 1975, U.S. automobiles didn’t have catalytic converters. Environmental problems from smog made these devices necessary. During the early 20th century, it was common to see major metro areas like New York and Chicago blanketed in thick smog. And with that smog full of pollutants, it would burn your eyes and make you cough. Los Angeles averaged around 200 smoggy days per year during the 1960s. But then came the Clean Air Acts of 1963 and 1970. Lead was also removed from most gasoline and catalytic converters were required on all vehicles.

Since converters are essential to reducing pollution, it’s illegal in most states to remove them. Federal law also prohibits the removal of a functioning converter. You also can’t swap them for converter replacement pipes.

How To Tell Your Catalytic Converter Has Gone Bad

Catalytic converters are made to go the distance. Most models last over 10 years. But converter problems can and do develop. Clogging is one common issue, resulting from engine coolant leaks. Putting leaded gas in your tank can also damage your converter. Your unit may also overheat thanks to misfiring spark plugs, leaking exhaust valves or faulty oxygen sensors. And believe it or not, thieves sometimes steal converters. That’s because they contain precious metals like rhodium, palladium and platinum.

Depending on what kind of problem your converter has, you may need to either unclog it or replace it altogether. You’re probably wondering, “How much is a catalytic converter?” Costs can run as low as $200, but high-performance versions can price out at $2,200 or more. Most converter problems are easy to spot by their symptoms:

  • Slow engine performance
  • Sluggish acceleration
  • Dark gray or black exhaust smoke
  • Too much heat under your vehicle
  • Rotten egg smell from your exhaust

Replacing Your Catalytic Converter

You wouldn’t replace a converter as often as, say, your brake shoes or rotors. But you should be prepared just in case you must swap it out. Fortunately, shopping for your replacement is easier than you may think. Most retailers offer a make/model search or its free VIN lookup tool to help you find one that fits your vehicle.

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