Can You Drive With A Bad Catalytic Converter?


In this article, we will discuss whether or not you can drive with a bad catalytic converter. We’ll discuss what it is, what is its function, and why we should think twice before driving a car with a bad one.

What Is A Catalytic Converter?

The purpose of the catalytic converter is to reduce major pollutants that are produced by automobile engines. These can be a nuisance or even harmful to the environment around them.

There are three major pollutants of the combustion process:

  • Carbon monoxide (CO), which is a poisonous gas.
  • Hydrocarbons and other unburned organic compounds that contribute to the production of smog.
  • Nitrogen oxides that contribute to acid rain and smog. These pollutants also cause allergies in some people.

The catalytic converter converts these harmful pollutants into less harmful compounds before they leave the car’s exhaust system.

Most catalytic converters look like a stainless steel or metallic cylinder located between the engine and the muffler. As a car owner, you would normally never see it.

It’s kind of like a small chemical processing plant under your car. It uses precious metals as catalysts to convert the hydrocarbons and carbon monoxide gases into carbon dioxide and water on their way to the exhaust pipe.

can you drive with a bad catalytic converter cutaway

If the catalytic converter should ever break down or stop functioning, it is not always easy to know. You could be driving around without knowing it is totally kaput.

However, some vehicles are equipped with an exhaust sensor and a corresponding indicator light on the dash. This draws the attention of the driver to the faulty catalytic converter.

To better understand the need for catalytic converters, it’s helpful to know a little about how internal combustion engines work.

Car engines run on petroleum which is made up mostly of hydrocarbons. Apart from hydrocarbons, many chemical compounds are added to petroleum to improve the car’s performance.

All these compounds often do not burn cleanly, which results in the production of air pollution as a byproduct.

The pollutant gases generated by the car’s engine include a poisonous gas called carbon monoxide, as well as other volatile organic compounds and nitrogen oxides. These chemicals are not healthy to breathe, and create visible smog.

After combustion, the exhaust gases from the engine flow through a catalytic converter. Inside, is a dense honeycomb structure of ceramic, which is coated with catalysts.

The honeycomb structure ensures that the gases come in contact with large areas of the catalyst during their passage through the honeycomb structure, so they are converted more quickly and efficiently.

These catalysts are usually metals like platinum, rhodium, palladium. Modern catalytic converters use gold mixed with these metals as catalysts. Gold is actually cheaper than the other metals and increases oxidation, which reduces pollutants more efficiently.

The honeycomb structure ensures that the exhaust gases are exposed to the maximum surface area of the catalyst. After the hot gases pass through the catalytic converter, only nitrogen, oxygen, carbon dioxide gases, and water vapor come out of the exhaust of your car.

catalytic converter on a car

How Long Does A Catalytic Converter Last?

Usually, a catalytic converter will last throughout the car’s lifetime, but sometimes it can malfunction or get clogged, and needs to be repaired or replaced.

As your car gets older all the metals that act as catalysts in the converter may also be used up, which can cause the converter to lose its effectiveness. In this case, too, the catalytic converter should be replaced.

Apart from internal clogging, sometimes road debris may hit the external cylinder of the catalytic converter and damage it significantly enough to affect its functioning.

How To Check For A Clogged Catalytic Converter?

Normally your car’s system diagnostics will alarm when the catalytic converter gets clogged.  The best way to confirm this is to dismantle the catalytic converter and observe it manually for any signs of clogging.

The examination and cleaning can only be performed by a qualified mechanic who has the necessary tools and training.

How Long Can You Drive With A Bad Catalytic Converter?

You can usually drive your car for a long time even with a partially clogged converter. However, it will affect the performance of your car. If the converter is completely clogged then the car engine may run rough, or in extreme cases, not run at all.  

In case your converter is completely clogged, then it should be immediately replaced. It’s not a good idea to drive your car if the converter is clogged, particularly if you are living in an area with smog checks.

In some areas, it is illegal to drive a car with a clogged catalytic converter as it releases pollutants that are bothersome to the surrounding environment.

What Happens If I Don’t Replace My Catalytic Converter?

You will immediately get arrested and thrown into the gulag, without your one phone call. No, not really. Well, hopefully not….depending on where you live. 😉

inmate in gulag

Seriously though, most jurisdictions have regulations which require catalytic converters to be tested regularly and be kept in a functional condition.

Also, if the catalytic converter becomes contaminated, physically damaged, clogged, or overheated, your engine will perform poorly and it will lead eventually to engine shutdown.

A damaged or fused catalytic convertor might damage the other parts of your car, particularly the engine. This could cost you more in the long run if you wait too long to repair it.

If you find that the car is gulping noticeably more fuel than it used to, it could be a sign that your catalytic converter is clogged or faulty.

When there is resistance in the exhaust path of the combustion gases, your car’s engine has to work harder. This results in consuming more fuel, and therefore getting lower gas mileage.

Overheated catalytic converters are a serious fire risk. The exhaust system is one of the hottest parts of your car that runs through the entire length of the vehicle.

The catalytic converter is designed to work in a hot environment but it may still overheat if the car’s engine isn’t operating normally.

If the engine doesn’t burn the fuel efficiently, extra chemical compounds end up in the exhaust system. The catalytic convertor then has to work extra hard which makes it even hotter than usual.

Though it should operate around the temperature range of 1200oF to 1600oF, a clogged converter can get up over 2,200oF.

This causes long-term damage not only to the device itself but also to the car’s surrounding parts. It could even scorch the insulation lining and carpeting in the passenger cabin.

Can My Catalytic Converter Be Stolen Easily?

You may be unfortunate to wake up one morning to find that your catalytic converter has been stolen. For a dedicated thief who knows about cars and has the right equipment, this is not difficult. He can cut off a couple of pipes and steal your catalytic convertor easily and fairly quickly.

catalytic converter location

A catalytic converter contains precious metals in the form of platinum, rhodium, palladium, or even gold – all of which have value for metal dealers who sell them on the black market.

But don’t worry. If that ever happens to you, you’ll know it as soon as you start your car. That’s because it will sound like a really loud hot rod! That’s because there is no longer anything muffling the exhaust sound.

Symptoms Of A Faulty Catalytic Converter

Here are the main symptoms of a catalytic converter that is either clogged, or has given up the ghost:

  • Check Engine Light: Most cars now have built-in diagnostic systems which include monitoring of the catalytic converter. If the amount of pollution coming out of your exhaust is over a certain limit, your check engine light will come on. This will inform you that the catalytic converter is faulty and not working sufficiently.
  • Your car doesn’t start easily: If the catalytic converter is clogged and exhaust gases cannot pass through to the tailpipe, it can cause your engine to stall from increased exhaust backpressure. It may happen that your car runs normally for a few minutes, but then it starts sputtering or stalls out altogether. This could be a sign of a clogged catalytic converter.
  •  Engine misfiring: The catalytic converter can overheat and it may result in the engine misfiring.  It may mean a very rich unburned fuel mixture is entering the catalytic converter. The condition is dangerous as the fuel may ignite within the convertor which can melt the catalyst components.
  • Degraded performance: When accelerating or going uphill power is lost if the catalytic converter is clogged. Poor engine performance occurs because of the backpressure created by the choked catalytic converter, which prevents the engine from performing efficiently.  
  • Poor mileage: A decrease in the gas mileage from normal could indicate there is something wrong with your catalytic converter. Your car’s engine has to work harder if there is resistance in the exhaust line, which results in higher fuel consumption.
  • Overheated engine:  A clogged catalytic converter is similar to a plugged exhaust pipe. When the ceramic coating reaches the melting point, it could affect the normal flow of the exhaust gases. This could lead to overheating of the engine.

Final Thoughts

A catalytic converter is an important part of your car. It is often ignored, which results in poor performance of your engine output.  You should always get your catalytic converter inspected by a trained mechanic as per manufacturer’s recommendation.

Many jurisdictions have their own requirements of routine inspections, as well.

In the end, sure, you can usually drive with a bad catalytic converter… but it probably ought to be driving right to a repair shop.

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