Last Updated: 06.04.2022

The catalytic converter is part of the exhaust system that treats toxic gasses to make them harmless to the environment. Thus, if the catalytic converter is damaged, the result is increased pollution and poor engine performance. It can also lead to engine failure. 

Although the first recommendation by most people is to replace the catalytic converter, there is one more thing you can try: unclog it. 

If the converter issue can be remedied by unclogging, you might be able to fix it without having to go to a mechanic. An excellent way to cut down some costs, right? Keep reading to learn how to unclog a catalytic converter correctly and safely. 

Check If Your Catalytic Converter Is Clogged

catalytic converter picture

Before starting to unclog the converter, you need to determine if it is indeed clogged. So, here is how to know if your car has a clogged converter. 

The simplest method is by using an OBD2 scanner. Here, you only need to plug in the scanner and turn on the engine. The scanner will generate a code that you can check on the vehicle manual to know if the converter is clogged. 

If your engine misfires because of a rich fuel mixture or other reasons, there is a danger of melting the converter. Eventually, it results in clogging. So, if you have noticed regular misfiring on your car, the catalytic converter should be checked right away. 

Does your engine struggle when starting? Is the performance poor? Is there a smell of sulfur when your engine is running? If your answer to one or all of these questions is yes, one of the possible causes might be a clogged catalytic converter.

How to Unclog a Catalytic Converter 

There are two popular methods for unclogging a clogged catalytic converter. Let’s check them out.

Option 1: Make the Catalytic Converter Unclog Itself 

This is the simpler, faster, and most straightforward method, but it only works when the clogging is not extensive. Definitely, you should start with this method before making the decision to use the second option. 

Here’s how it works: 

  • Select a good catalytic converter cleaner depending on your car. 
  • Fill the gas tank with about 15 liters or 50% level. 
  • Pour the cleaner into the fuel tank and rev the car at about 3000 RPM for 30 minutes. Driving until the gas tank is near empty can also work. 
  • Then, recheck the car using the OBD2 scanner to see whether the code for clogged converter has disappeared.

Option 2: Unclog the Catalytic Converter Manually 

If the clogging is too much, the first method will not work. This is why you should consider a more comprehensive method, and unclogging the converter manually will be an excellent choice. 

So, let’s look at the steps that you should follow. 

What You Need 

First, you need to gather all the required items and reagents, including: 

  • Clean towel
  • Safety equipment: apron, goggles, and gloves 
  • Wrench 
  • Jack
  • Degreaser 
  • A container 
  • High-pressure washer 

Step 1: Prepare for the Unclogging Job

prepare the unclogging job

Put on protective clothing. Then, park your car on a flat surface and allow the car to cool down. This is important because the exhaust system can get really hot, and touching them could result in burns. In some cars, the temperature can go way beyond 600°F.

Step 2: Remove the Catalytic Converter From the Car

remove the catalytic converter

To safely remove the catalytic converter from the car, you need to first locate it. Using a jack, lift the car to a comfortable position where you can easily unfasten it. 

In most cases, the catalytic converter is located near the rear of the car, but there are instances when you might need to remove the entire exhaust line. 

Using a wrench, unfasten the bolts to release the cat-con from the rest of the exhaust line. Because the converter is located underneath the car, the nuts can be rusty and stubborn to loosen. So, apply some oil to loosen them faster and easier. If the converter was welded to the rest of the exhaust system, it is best to work with a mechanic to get it separated. 

Step 3: Inspect the Catalytic Converter Carefully 

Once you have correctly removed the catalytic converter, carefully check it and establish its status before moving to the next step. If the converter is melted or broken, unclogging it might not work. In such a case, the best method would be to replace it right away.

inspect the catalytic converter

If you find that the converter is still operational, but it is approaching its end of life, make sure to start planning for a replacement. This should also be an excellent time to start shopping for a replacement. 

Step 4: Clean the Cat-Con With a Towel and Prepare Water With Washing Detergent

Grab a clean piece of towel and start cleaning the catalytic converter right away to clear off the debris. Using a pressure washer, thoroughly wash off the stubborn dirt and debris from the inner part of the catalytic converter.

prepare water with washing detergent

Because the inner part of the catalytic converter is fragile, you have to control the water pressure to reduce the risk of causing more damage. Instead of using very high pressure, consider working on the catalytic converter from both sides. Then, prepare a mixture of hot water with washing detergent to help remove even more from the converter. 

Step 5: Soak the Catalytic Converter for 45 Minutes 

If the catalytic converter has some stubborn dirt that cannot be removed by wiping or by using a pressure washer, it is time to loosen it. Put the hot water with the washing detergent you prepared in step 4 into a large container and add some degreaser. Now, soak the catalytic converter and leave it for about 45-60 minutes.

soak the catalytic converter

Remember not to leave the catalytic converter there for a long time to avoid causing further damage. You might want to inspect it after every 20 minutes to check the progress. If all the dirt has loosened and fallen off in 30 or 45 minutes, remove it from the hot water-degreaser solution. 

Step 6: Let the Catalytic Converter Dry 

After removing the catalytic converter from the soaking container, do not reinstall it before it is completely dry. It will be a good idea to start by rinsing it with clean water. You might also want to use a pressure washer with clean water to clear off all the detergent from the surfaces.

let the catalytic converter dry

Dry the catalytic converter with a towel to remove the extra water on the surface. Then, allow it to stay for a couple hours until it dries completely. Make sure that all the parts, including the meshed inner sections, are dry.

Step 7: Re-attach the Catalytic Converter 

After following all the steps we have listed above, it is time to test whether the catalytic converter has been unclogged and restored to superb condition. Put it back in the car and firmly fasten it. 

Now, it is the moment of truth.

man to test drive the car

Go out for a test drive. After about one hour or so of driving around, use the OBD2 scanner to check for the clogged system error code. If it has disappeared, and the engine light is also not there anymore, pat yourself on the back for a good job done. Congratulations!

If the engine light and the scanner code for the clogged catalytic converter are still there, then the system is damaged beyond repair. Therefore, it is time to go to the repair shop for expert help or to get a new one installed.


What are the main signs of a clogged catalytic converter? 

The best method to establish if your car’s catalytic converter is clogged is by using the OBD scanner. If it gives the code for a clogged system, you need to act right away before further damage happens to the car. Other signs of a clogged system include: 

  • Difficulty starting the engine
  • Failed emission test
  • The car returns very poor fuel economy
  • Regular misfiring of your car
  • If your car’s engine oil is leaking 
  • Rough acceleration and rough idle
  • Lean fuel mixture

Can a car clean its catalytic converter? 

Yes, it can, but your input will be required. Indeed, it takes only a few steps, and if the catalytic converter is not so clogged, this might be all that you need. To use this method, you need to get some catalytic converter cleaner and add it to the fuel tank. Then, drive around for about half an hour. The cleaner will get through the system and into the cat-converter to help clean it. 

However, this method rarely works when the clogging is too much, or when the cat-converter is damaged. If it does not clear the engine light, you better try cleaning the cat-con manually. 

Is it a good idea to hit the cat converter with a hammer?

Yes, hitting the catalytic converter with a hammer is part of the system’s diagnostics when checking its condition. Because the converter is made of a substance that disintegrates because of physical impact, hitting with a hammer can help you understand its condition. 

If you hit the converter lightly with a hammer and the substrate used on its interior disintegrates, it indicates that it has seen the better days. Therefore, you should not even consider unclogging it. Instead, you should have the converter replaced immediately.

What are the main causes of catalytic converter failure?

When a cat-con is damaged, it can mean a lot of trouble for your car and you. If not handled right away, it could result in high costs of car maintenance. The main causes of failures in your cat-con are mechanical damage and overheating. 

Related: Learn how to recognize bad EVAP canister symptoms


A catalytic converter is very important, especially now that more efforts are directed at cutting down emissions. Therefore, you must be alert for the signs of a clogged catalytic converter. Then, use the steps we provided in this post on how to unclog a catalytic converter.

The process is not complicated and does not require specialized tools. When done correctly, you are sure of clearing that engine light and OBD code for clogged cat-con. This could save you some money that could have gone to buying a new cat-con and repair charges. 

One more thing: Scotty Kilmer, your video was awesome!