What Happens If You Don’t Fix Catalytic Converter?

By July 27, 2020October 18th, 2020Common Questions, Maintenance

A bad catalytic converter will reduce car performance, increase emission and decrease fuel efficiency. A bad catalytic converter will not damage your other car parts. Actually – you can run your car without a catalytic converter. This is usually done to improve the car performance at the cost of absolutely horrible emission.

But why exactly are these happening? Let’s cover catalytic converter in detail 🙂

What Is The Function Of A Catalytic Converter?

To produce power your car has to create combustion by igniting fuel in the combustion chamber. This combustion also creates toxic exhaust gases: 

  • Hydrocarbons
  • Carbon Monoxide
  • Nitrogen Oxides


These exhaust gases must first be converted into non-toxic gases before they are released into the atmosphere. And that’s where the catalytic converter comes in.

Catalytic converter is made of ceramic and consists of other materials like Platinum Palladium and Rhodium. Without going into too much detail, these materials can convert the toxic exhaust gases into non-toxic ones like Carbon Dioxide, Oxygen and Nitrogen. In case you didn’t notice – a catalytic converter contains rare materials that could be sold for high. And that’s why catalytic converter theft is very common. Now you know 😉 

Catalytic converter is fun on your exhaust system just before the muffler.

illustration of a car exhaust system
Catalytic Converter in the exhaust system

How Does Catalytic Converter Get Damaged?

Poor Air / Fuel Ratio

Just a quick recap, to deliver power your car needs to burn fuel and create combustion. this combustion will then consume oxygen available in the combustion chamber. 

An optimal air-to-fuel ratio means that there is enough oxygen in the combustion chamber for all the injected fuel to be burnt completely. If too much fuel is injected – this means not all the fuel can burn and they will escape from the combustion chamber into the exhaust system.

This unbuned fuel will reignite when it reaches the catalytic converter which will cause an abnormally high temperature in the catalytic converter causing it to melt down.

The most common causes of poor air-to-fuel ratio include 

  • Faulty Oxygen sensor
  • Faulty fuel injector
  • Clogged air filter

Fractured Catalyst

The catalytic converter contains ceramic catalysts – that are fragile. To prevent it from being broken, the ceramic catalyst is usually surrounded by a layer of insulating mat. While this mat can protect the ceramic, the mat itself can also be broken by external factors – commonly being road debris and broken catalytic converter hanger.

Once the insulating mat is broken, the ceramic catalyst is bound to shatter into smaller pieces and rattle around inside the catalytic converter. Sooner or later, these ceramic pieces will disturb the exhaust flow and create extra pressure, preventing the exhaust gas from quickly flowing out. This in turn will cause extra heat and destroy the catalytic converter even further.

Short Trips

If you find yourself regularly driving short trips, then you are more prone to clog your catalytic converter. If you only take short trips then there won’t be much exhaust gases produced by the car.

This means the catalytic converter will not reach high enough temperature to convert all the hydrocarbons produced by combustion. As Time passes these hydrocarbons will build up in your catalytic converter and cause it to clog.

I recommend you at least take your car for a 15 minutes ride once a week. There will be enough heat from the exhaust gas to allow your catalytic converter to do its work and unclog itself.

Performance Modifications

Oftentimes, enthusiasts look to increase the performance of their cars by installing performance modifications like superchargers, turbos and nitrous. These performance modifications do work. However, the remaining stock parts simply cannot handle it. The extra speed is generated by having a bigger combustion. Which means extra pressure, extra heat and extra exhaust gases – leading to wear and tear of other stock parts like exhaust system and catalytic converter.

GIF of dancing nos man
Performance modification like Nitrous can cause wear and tear damages to catalytic converter.

Catalytic Converter Left Unfixed

Reduced Performance

A clogged catalytic converter means that the exhaust gases cannot flow out of the car as quickly as it can. This will trap the exhaust gases inside the exhaust and combustion chamber – leaving no room for extra air to enter. Without fresh air, your car engine cannot create optimal combustion in the next cycles – leading to reduced performance. Especially when you attempt to accelerate. 

Bad Fuel Efficiency

A clogged catalytic converter can also reduce fuel efficiency. Similar to the point above, a clogged catalytic converter will not allow exhaust gases to flow easily – essentially trapping them inside. This will occupy the available space inside the exhaust system and combustion chamber – leaving no room for fresh air. Majority of the fuel injected into the combustion chamber cannot ignite without fresh air – causing it to be wasted instead.

Horrible For The Atmosphere 

Still remember what the catalytic converter does? If you already forget, a catalytic converter converts toxic exhaust gases into non-toxic ones. If your catalytic converter is bad, what do you think will happen? More toxic gases escaping from the exhaust, duh! These gases are extremely harmful to the environment. Especially Carbon Monoxide – who destroys the earth’s Ozone layer, causing everything to heat up!

Failed Emission Test

If you don’t care about the earth’s Ozone layer, then what about caring for yourself? Without a working catalytic converter, you will definitely fail the emission test. The toxic exhaust gases from the combustion will flow straight out! Check if your state has a regular emission test. If it does, then you definitely must fix your catalytic converter.

Image of exhaust with black smoke
Exhaust gases that are not treated properly by catalytic converter

Can Bad Catalytic Converter Damage My Engine?

A bad catalytic converter will not cause major damage to your engine. The most common impacts are reduced performance and bad fuel efficiency. When it comes to physically damaging your engine, a bad catalytic convert can only cause wear and tear damages. 

Clogged catalytic converters will reduce air flow and trap exhaust gases within the exhaust system. This in turn will increase pressure and heat in the exhaust system. Over time, the increased pressure and heat will cause wear and tear damages on the exhaust and also other surrounding parts.

Can A Car Run Without a Damaged Catalytic Converter?

For sure! A catalytic converter is only used to convert toxic gases into non-toxic ones. In fact, you can even drive your car without a catalytic converter. This is commonly done to increase the performance of a car – also known as straight piping. 

Straight piping is when you remove the muffler and catalytic converter from an exhaust system. This will greatly improve the air flow of your exhaust gases. Which means the exhaust gases can directly exit from the car without any blockers in its path. I cover straight piping in this article if you are interested. 

Image of straight pipe exhaust
Straight pipe exhaust does not have catalytic converter. This will allow the car to run with more power at the cost of horrible emission.

How To Fix Bad Catalytic Converter?

Replace it

The easiest way to fix a bad catalytic converter is to… well, replace it! However, this can be costly at $1000. Plus, you might not be willing to spend as much – especially if your car can still run without it.

Remove The Catalytic Converter

Remember I said your car could still run without a catalytic converter? Well, this could be an option for you. By removing the catalytic converter, you will not have any catalytic converter problems and you will also have a slightly increased performance. Although this comes with many other downsides like extremely bad emission and consistently failing the emission test!

I will not recommend this option, unless your car is a project car that you only drive once a week on the track.

Clean With Laundry Detergent 

This method requires you to take off your catalytic converter and soak it in  laundry detergent water overnight. The insides of a catalytic converter is made up of thin honeycomb structures that could get clogged easily. Soaking the catalytic converter overnight on soapy water like laundry detergent can help to remove the dirt. This method works surprisingly well, but it could be a hassle, because you have to take off the catalytic converter first.

Image of Catalytic Converter on Detergent Water
Catalytic converter on detergent water

Clean With Lacquer Thinner (NOT)

You may find suggestions to fill a gallon of lacquer thinner on your half empty gas tank. This will supposedly clean out your catalytic converter as you drive. I personally do not recommend this method. We do not know exactly what’s included in the lacquer thinner. For you to be putting such a solution into your gas tank is absolutely not worth it. 

Image of Lacquer Thinner
A gallon of lacquer thinner

How To Maintain A Catalytic Converter?

Here is a list of things you could do to preserve your expensive catalytic converter. 🙂

  • Go easy on the bumps. Ensure they do not hit your catalytic converter
  • Avoid puddles. Catalytic converter needs a high temperature to work. Coming in contact with water will rapidly cool it down and cause clogging
  • Be careful on performance modifications. Do not push your stock parts to the absolute max. 
Ifandi L.

Ifandi L.

Passionate about everything mechanical. Ifandi has been involved with motorcycles and cars since the old days - in his family's auto parts shop. Want to keep in touch? Scream "STRAIGHT PIPEEEEE" at the top of your lungs and Ifandi will show up.

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