Is It A Good Idea Driving With A Bad Catalytic Converter?


In this article, we will discuss what a catalytic converter is, what is its function, and why we should think twice before driving a car with a bad catalytic converter.

Let Start With What Is A Catalytic Converter?

The purpose of the catalytic converter is to reduce major pollutants that are produced by the automobile engines which are harmful to the environment.

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 and increase global warming.
  • Nitrogen oxides that contribute to acid rain and smog. These pollutants also cause allergies to some people.

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

The catalytic converter is stainless steel or metallic cylinder located between the engine and the muffler that you as a car owner would normally never see.

The catalytic converter is a small chemical processing package that 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.

If the catalytic converter should ever break down or it stops functioning, then it is not always easy to know that it has broken down unless you have an indicator light for it on your car console.

Why automobile engines produce pollution?

Car engines run on petroleum which is made up 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 like carbon monoxide, as well as other volatile organic compounds and nitrogen oxides. These chemicals are bad for the environment,  create smog, and also contribute to global warming.

What happens inside the converter?

The exhaust gases from the engine after combustion flow through a catalytic converter which has a dense honeycomb structure of ceramic coated with the 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 and 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 convertor only nitrogen, oxygen, carbon dioxide gases, and water vapour come out of the exhaust of your car.

How long a catalytic convertor lasts?

Usually, a catalytic converter will last throughout the car’s lifetime, but sometimes it can malfunction, 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 convertor gets clogged.  The best way to confirm is to dismantle the catalytic convertor and observe it manually for any signs of clogging.

The examination and cleaning can only be performed by a qualified mechanic.

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 not run at all.  

In case your converter is completely clogged, then it should be immediately replaced. Never try 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 harmful to the environment. In this case, you need to replace the catalytic convertor right away as you may be fined by the police if you are caught.

What happens if you don’t replace your catalytic converter?

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.

A bad catalytic converter will cause poor gas mileage

If you find that the car is consuming too much fuel then it could be a sign that your catalytic converter is clogged or going bad.

When there is resistance in the exhaust path of the combustion gases then your car’s engine has to work harder, consume more fuel, causing your car to give a lower mileage.

Can a catalytic converter catch fire?

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 overheat if the car’s engine isn’t operating normally.

If the engine doesn’t burn the fuel efficiently, due to any malfunction, a lot of 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.

A clogged catalytic converter which should operate around the temperature range of 650oC to 870oC can cross up over 1,200oC. This causes long-term damage not only to the device itself but also to the car’s surrounding parts. It could scorch the insulation lining and carpeting in the passenger cabin.

Your catalytic converter can be stolen!

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.

Catalytic converter contains precious metals in the form of platinum, rhodium, palladium, or even gold, all of which have value for metal dealers and can be sold in the black market.

Here are some of the symptoms of a bad catalytic converter that you should know:

  • Check Engine Light: Most cars now have built-in diagnostic systems which include monitoring of the catalytic converter. If the amount of pollution is 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 not working sufficiently or it is all clogged up.
  • 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 is 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 convertor which prevents the engine to perform 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.

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

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