What Does The Catalytic Converter Do, And Why Should You Replace It?

The first question most car owners will want answered is this: what is a catalytic converter, and what does it do in vehicles? As Engineering Explained, ICE vehicles, diesel or gasoline, run by reacting fuel with oxygen in the air.

While cars and trucks have gotten cleaner, emissions-wise, over the years, this combustion still results in waste products. Carbon monoxide and dioxide, NOx, and soot are the common by-products, with diesel engines also producing sulfur by-products called SOx.

Many of these chemicals are either downright toxic on their own or create harmful conditions when they hit the open air. This is where the catalytic converter comes in. Inside is a ceramic honeycomb, which holds several precious metals. 

These are usually platinum, rhodium, and palladium and function as catalysts. Basically, they help the noxious gases, like CO and NOx, react with oxygen left in the exhaust flow. This converts the gases into less toxic forms. The ceramic not only holds the catalysts in place but also gets hot and stays hot so the catalysts can do their jobs.

Because oxygen is so important for proper catalytic converter operation, modern vehicles have sensors in place throughout the exhaust to monitor how much of it is present. If you’ve ever had to have an O2 sensor replaced, that’s what it was doing. Using these sensors, the vehicle’s computer can monitor if the fuel-to-air mix is too rich or lean and adjust the fuel injection to compensate.

If it didn’t, not only would your engine burn more fuel and foul its spark plugs, your catalytic converter would stop working.

Why do Catalytic Converters fail?

Catalytic converters actually don’t fail that often, according to Viper Motorsports. Eventually, the internal components fail with age. However, many converters last the vehicle’s lifetime or roughly 15 years.

However, catalytic converters can fail early if they clog. Unburned fuel in the exhaust can get stuck in the ceramic honeycomb. Not only does this make the converter less effective, but there’s also raw fuel sitting in a hot place with air blowing past it. Eventually, the fuel ignites, melting the ceramic and ruining the converter.

NAPA also reports that coolant and oil can leak into the exhaust from leaking gaskets. They may not burn as hot as the fuel, but they can still clog the converter.

All this means replacing the catalytic converter, which isn’t cheap and can get even more expensive. 

When Should You Replace the Catalytic Converter?

There are several signs that your catalytic converter is failing. The most obvious is a strong smell of rotten eggs. One engine emission is hydrogen sulfide, which normally gets converted into sulfur dioxide. However, if the catalysts fail, the hydrogen sulfide builds up, creating a stink.

Cars.com also reports that problems with accelerating, as well as excessive engine heat, can be a sign of catalytic converter failure. But because other car problems can lead to converter failure, identifying and repairing them beforehand is also important.

Oil leakage has its own smell and the physical sign of blue-black smoke from the engine and tailpipe. Coolant leakage causes white smoke. While unburned fuel leakage can be due to a number of problems, the biggest signs are misfires and the dreaded “Check Engine” light.

Conclusion

If any of this sounds like your vehicle, check it as soon as possible. Replacing a catalytic converter may be expensive, but it’ll get even more expensive when a worn-out catalytic converter is not changed in a vehicle.