Maintenance Tips, Tricks And Hacks For Your Vehicle

How To Fix a Catalytic Converter That Is Clogged (Answered!)




If your catalytic converter is clogged, you may be wondering how to fix it. A clogged catalytic converter can cause a lot of problems for your car, including decreased fuel efficiency and increased emissions.

In this blog post, we will discuss some tips and tricks that can help you unclog your catalytic converter and get your car running like new again!

Key Takeaway

  • To fix a catalytic converter that is clogged, you will need to a pour full bottle of a catalytic converter and about 20 gallons into the gas tank and then drive the vehicle for about 150 miles.
  • A catalytic converter is a vehicle emissions control device that converts harmful pollutants in the car’s exhaust gas into less harmful substances through a redox (reduction and oxidation) reaction.

What Does The Catalytic Converter Do?

A catalytic converter is a device that uses a catalyst to convert exhaust emissions from an internal combustion engine into less harmful substances.

Catalytic converters are made from several different materials, but the most important component is a catalyst. The catalyst is usually made from platinum or palladium, and it helps to convert the exhaust fumes into less harmful gases.

The other parts of the converter help to keep the catalyst in place and protect it from being damaged by high temperatures.

The main function of a catalytic converter is to reduce the emission of pollutants. It does this by chemically converting the pollutants into harmless gases.

There are three main types of catalytic converters: oxidation catalysts, reduction catalysts, and three-way catalysts. Oxidation catalysts help to convert carbon monoxide and hydrocarbons into carbon dioxide and water vapor.

Reduction catalysts help to convert nitrogen oxides into nitrogen gas and oxygen gas. Three-way catalysts are a combination of both oxidation and reduction catalysts and help to reduce all three types of pollutants.

The first step in making a catalytic converter is to create the honeycomb structure that will serve as the foundation for the catalyst material.

This structure can be made from a variety of materials, but the most common type is ceramic. Once the honeycomb structure has been created, it is coated with a thin layer of platinum using a process called chemical vapor deposition.

Catalytic converters are an important part of a car’s emission control system. They are required by law in many countries.

This is how a catalytic converter works to clean up the exhaust fumes from your car.

How To Fix a Catalytic Converter That Is Clogged

  • Get a catalytic converter cleaner
  • Scan the vehicle with an OBD2 scanner. You should get a P0420 code suggesting that the cat is clogged.
  • Add about 1.25oz of cat cleaner to a gallon of fuel. For a full tank, it is usually 20oz cat cleaner.
  • Drive the vehicle for 150 miles, or let it idle for 30 minutes.

If your catalytic converter is clogged, you’re going to want to take care of the problem as soon as possible.

Not only will a clogged converter cause your car to run poorly, but it can also lead to more serious problems down the road. Here is how to fix a catalytic converter that is clogged:

1. Required items

2. Scan your vehicle for error codes

How To Fix a Catalytic Converter That Is Clogged

If you have a check engine light and you suspect that your catalytic converter is triggering it, you need to verify it. Catalytic converters are very expensive.

This is why before you replace your clogged catalytic converter, you need to try and fix it. A catalytic converter can trigger an error code when it loses only 5% of its efficiency. This is why we always try to clean it first.

OBD scanners are used to diagnose issues with your vehicle. They can be used to check for engine codes, transmission codes, and more. OBD scanners can also be used to reset your check engine light. Here is a step-by-step guide on how to use an OBD scanner:

First, you will need to purchase an OBD scanner (see the price on You can find these online or at your local auto parts store. Once you have your scanner, you will need to connect it to the diagnostic port in your vehicle.

The location of the diagnostic port will vary depending on your vehicle’s make and model. Consult your owner’s manual or an online search if you are unsure of where to find it.

Once the scanner is connected, you will need to turn on your ignition (do not start the engine). The scanner will then begin scanning your vehicle. It may take a few minutes for the scan to complete. Once it is finished, you will be able to view the results on the screen of the scanner.

A trouble code associated with a clogged catalytic converter is P0420 – Catalyst efficiency below threshold. If you see this code, you have a clogged catalytic converter and you need to fix it.

3. Pour the cleaner into the gas tank

How To Fix a Catalytic Converter That Is Clogged

Catalytic converters can become clogged for a variety of reasons. One common reason is the build-up of carbon deposits on the catalyst surface.

This can happen if the engine is running too rich or if there is an oil leak. Another reason catalytic converters can get clogged is from the use of leaded gasoline. Lead deposits can accumulate on the catalyst and eventually reduce its effectiveness.

If a catalytic converter becomes clogged, it will usually cause the engine to run poorly. The engine may misfire, have reduced power, or produce excessive amounts of exhaust fumes.

To fix a clogged catalytic converter, you need to pour a catalytic converter cleaner into the gas tank. Add a full bottle of cleaner to 20 gallons of fuel or 1.25oz per gallon of fuel.

A catalytic converter cleaner works by breaking down the carbon deposits that have built up on the catalyst, allowing it to work more effectively. When these carbon deposits are broken down, they are converted into gases that can then be expelled from the engine through the exhaust system.

This cleanser is typically added to your fuel tank and will be drawn into the engine as you drive.

4. Drive the car to get the cleaner working

With the catalytic converter cleaner poured into the gas tank, you can either drive the vehicle for 150 miles or rev the car to 2500 RPMs for about 30 minutes. Personally, I prefer driving the car because sitting in one place for about 30 minutes is way too boring.

When you drive the car, the catalytic converter cleaner that you added to the gas tank will travel through the fuel lines and into the combustion chamber. From the combustion chamber, it will go to the exhaust outlet manifold and directly into the catalytic converter. When the cleaner reaches the catalytic converter, it will start and clean the carbon buildup.

Inside the catalytic converter, there is a honeycomb structure that is designed to trap any large particles. This is where the carbon deposits build up the most. Once the catalytic converter is cleaned, the check engine light will disappear says RepairSmith.

Can a Clogged Catalytic Converter Cause Engine Damage?

A clogged catalytic converter can cause engine damage if the engine is not receiving enough oxygen. The catalytic converter helps to convert exhaust gases into less harmful substances.

If the converter becomes clogged, it can cause the engine to run lean, meaning that there is not enough air and fuel mixture in the cylinders. This can lead to serious engine problems such as piston damage and overheating.

If your car’s catalytic converter becomes clogged, it’s important to have it cleaned or replaced as soon as possible. Ignoring the problem could result in expensive engine damage down the road.

There are many causes of clogged catalytic converters, but the most common is the use of leaded gasoline. Leaded types of gasoline can deposit lead on the catalyst, which can then poison it and reduce its efficiency.

Another common cause of clogged catalytic converters is the use of oil-based lubricants on spark plugs. These lubricants can build up on the catalyst and eventually block it. Finally, any fuel or oil that leaks onto the exhaust system can coat the catalyst and reduce its efficiency.

If you don’t fix the catalytic converter, your car will eventually stop running. The engine will become less and less efficient, and eventually, it will just stall out. Your car will also produce a lot of smoky exhaust. If you live in an area with environmental regulations, you could be fined for driving a car with a faulty catalytic converter.

In extreme cases, the catalytic converter can catch fire, which is very dangerous. So it’s definitely not worth risking your safety or your wallet by driving around with a broken catalytic converter. Get it fixed as soon as possible!


Q: What is a catalytic converter?

A: A catalytic converter is a component in a vehicle’s exhaust system that helps to reduce harmful emissions by converting toxic gases and pollutants into less harmful substances.

Q: How does a catalytic converter become clogged?

A: A catalytic converter can become clogged due to a buildup of residue and deposits from the engine’s exhaust gases. This buildup can be caused by factors such as a faulty fuel-air mixture, engine misfires, or the use of low-quality fuel.

Q: What are the symptoms of a clogged catalytic converter?

A: Some common symptoms of a clogged catalytic converter include a decrease in engine performance, reduced fuel efficiency, sulfur smell from the exhaust, difficulty starting the engine, and the illumination of the “Check Engine” light.

Q: Can a clogged catalytic converter damage the engine?

A: Yes, a clogged catalytic converter can potentially cause damage to the engine. The increased back pressure created by a clog can lead to overheating, engine misfires, and even engine failure if not addressed promptly.

Q: How can I diagnose a clogged catalytic converter?

A: A mechanic can perform a diagnostic test using a pressure gauge to measure the pressure before and after the catalytic converter. If there is a significant difference in pressure, it indicates a potential blockage.

Q: Can I unclog a catalytic converter myself?

A: It is not recommended for a DIY approach to unclog a catalytic converter. Cleaning or removing the clog may temporarily solve the issue, but it is crucial to identify and address the underlying cause to prevent future clogs.

Q: How much does it cost to fix a clogged catalytic converter?

A: The cost of fixing a clogged catalytic converter can vary depending on the extent of the damage and the make and model of the vehicle. Generally, the repair or replacement cost can range from $500 to $2,500.

Q: Can a clogged catalytic converter be repaired?

A: In some cases, a clogged catalytic converter can be repaired by cleaning it with a specialized solvent or using a catalyst cleaner. However, if the converter is severely damaged, it may need to be replaced.

Q: How long does it take to fix a clogged catalytic converter?

A: The time required to fix a clogged catalytic converter depends on several factors, such as the severity of the clog and the availability of replacement parts. In most cases, the repair can be completed within a few hours to a day.

Q: How can I prevent my catalytic converter from getting clogged?

A: To prevent a catalytic converter from getting clogged, it is essential to maintain good engine performance and follow the manufacturer’s recommended maintenance schedule. This includes regular oil changes, using high-quality fuel, and addressing any engine issues promptly.

In Conclusion

In conclusion, fixing a clogged catalytic converter can be achieved in several ways, depending on the severity of the clog.

For minor to average clogs, using specialized catalytic converter cleaners or DIY methods like adding lacquer thinner to fuel or using a mixture of water and lacquer cleaner can be effective.



Vide Polowenski, Senior Mechanic

The information in this article is current and up-to-date in accordance with the latest mechanic SOPs.

Please take the time to leave a comment if this article has helped you in any way, you need additional help, or you have a suggestion.

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