Clean your Catalytic Converter in 5 easy steps using Cataclean

We help you to understand common issues with a catalytic converter, how to know when you need CataClean, and how to use it to clean out your catalytic converter in 5 easy steps.

Is your catalytic converter throwing error codes? Are you getting check engine lights? Is there a rotten egg smell emanating from the underside of your vehicle? These are all signs that you may need to address your catalytic converter.

By Maurice Rodriguez
December 30, 2021

A catalytic converter may seem like an unassuming device that only exists to cause you anxiety. Between it throwing engine codes and thieves trying to hack it off for a quick buck you may wonder what it does in the first place. We will answer all your questions on how to identify the typical symptoms of a faulty catalytic converter, how to quickly check error codes for free or in your home garage, and how to clean it out with CataClean in under an hour.

About Cataclean

Cataclean is produced in the UK by CataClean Global and has been making a range of “pour and go” products that meet strict EU environmental restrictions regarding fuel system cleaners since 1995.

Cataclean is a patented solution for cleaning fuel and exhaust systems and has been shown to reduce vehicle emissions by up to 60%. Cataclean is endorsed by industry experts, has many 5 star reviews on Amazon, and is recommended by Car Mechanics and Professional Mechanics Magazine.

Cataclean is legal in 50 states (including California), is EPA approved, and is safe on gasoline, diesel, and hybrid engines.

How does Cataclean work?

Cataclean contains EPA-approved solvents that can dissolve carbon deposits that build up over time as your catalytic converter traps harmful emission particles from entering into the atmosphere. It is a pour-and-go solution that can be used to eliminate catalytic converter issues like poor acceleration, foul sulfur smells, reduced engine efficiency, and check engine lights.

What is a catalytic converter?

A Catalytic Converter is an emissions device that is able to convert exhaust gases and remove or decrease the amount of carbon, hydrocarbons, and other pollutants that enter into the atmosphere. They are used by all major engine manufacturers in gasoline and diesel engines to meet federal EPA guidelines regarding emissions. They ensure the engine burns its fuel completely and efficiently and this is why it can cause havoc in your vehicle if it is not operating at optimal levels.

Vector illustration of the Car Catalytic Converter – cross-section.

5 Symptoms your catalytic converter needs to be cleaned

Where do I buy Cataclean?

These prices reflect research that was done in 2022 and represent prices from a variety of vendors. The average price of Cataclean is $25.38 for the vendors we price-checked. This is a great value for potentially clearing up check engine lights, poor performance, and foul smells.

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Will Cataclean clear a P0420/P0421 code?

If you have a check engine light and you either scan your own codes with a handheld ODB2 Scanner (you can pick one up for less than $40) or take it to your preferred auto parts store and have them do it for you, there’s a good chance you came away with a cryptic P0420 code that says,” Catalyst System Efficiency Below Threshold (Bank 1).” P0421 is a similar code associated with Catalytic Converter issues, this code reads, “Warm Up Catalyst Below Threshold.”

Both codes indicate that your catalytic converter is not performing optimally and will cause exhaust gasses to not be converted into harmless emissions gases as it was intended. Your exhaust system could be emitting harmful pollutants, and gases into the environment which will lead to failing an emissions test.

While you may not notice any issue driving your car when this error code and check engine light are on, you should strongly consider taking some measures to fix the issue before it becomes a more serious problem.

In regards to Cataclean clearing out P0420 error codes, there is lots of anecdotal evidence from drivers that have used Cataclean that it MAY clear out your codes. There are several reasons why Cataclean is a good place to start if you get a check engine light and a P0420/P0421 error code. First, Cataclean is a fuel system cleaner and will remove carbon buildup that has been deposited all along your fuel system, clean out O2 sensors, and break down any build-up in your catalytic converter.

However, if you have other issues like faulty O2 sensors, or other codes along with the P0420/P0421 error codes these issues will continue to persist and will come back after you clear the initial P0420/P0421 error code. Now that you know what Cataclean is capable of doing and not doing you should be surprised as we were on how well Cataclean works on your catalytic converter works.

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How to Use Cataclean – Instructions on its use

Material List


Step 1. MOST IMPORTANT STEP! DO NOT SKIP! It is recommended by the manufacturer when using Cataclean to apply the product when the gas tank is at 4 gallons full or about a ¼ of a tank of fuel. If you know your vehicle’s fuel tank capacity this may be more or less. The ratio of one Cataclean bottle 500ml or 17 oz. to 4 gallons of gas is the optimum amount of gas to ensure the product is able to completely clean your catalytic converter at full strength.

Step 2. Remove the seal on the bottle and pour the entire contents into your vehicle’s gas tank.

Step 3. Drive your vehicle for at least 15 minutes to give the product a chance to work its way through. In a safe area, accelerate briskly to give Cataclean to burn out any carbon buildup.

Step 4.  After the recommended drive-in period, refill your gas tank as needed. 

Step 5. Once you’ve driven your car for 50 miles you can clear any error codes using your scanner. The error codes should not return if the issue was a dirty catalytic converter.


We were very surprised at how effective Cataclean was at cleaning out the catalytic converter and in some cases stopping error codes from returning. Some users have reported that they were also able to pass the emissions test using Cataclean. While we are skeptical it can help you pass an emissions test if your catalytic converter is actually damaged it certainly has shown it can clean out carbon buildup and O2 sensors. We think for under $30 at most places this is a great value and a good place to start when troubleshooting this kind of issues.

We hope this information was helpful with clearing your P420/0421 error codes and cleaning up your catalytic converter.

We are all things cars.

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