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The Best Catalytic Converter Cleaner 2021

Best Catalytic Converter Cleaner

Failing an emissions test can lead to expensive repairs. However, by using a catalytic converter cleaner, you can potentially save a lot of money. They are designed to dissolve dirt, varnish, rubber and carbon residue inside the exhaust system.

The best catalytic converter cleaner is the Cataclean 120007, which reduces carbon build-up and lowers emissions by up to 50%.

The cleaners work in a similar fashion as a fuel injector cleaner. They can be simply poured into the fuel tank at a specified ratio stated on the bottle. It’s important to note that most formulas require the engine to be at optimum working temperature.

Table of Contents

Best Catalytic Converter Cleaner

Catalytic Converter CleanerCompatibilitySize
Cataclean 120007Gasoline, Diesel & Hybrid473 ml
CRC 05063Gasoline Only335 ml
OXICAT CleanerGasoline, Diesel & Hybrid250 ml
Solder-It CAT-1Gasoline Only473 ml
MotorPower CareGasoline, Diesel & Hybrid250 ml
Hi-Gear HG3270sGasoline Only444 ml

The main purpose of a catalytic converter cleaner is to remove carbon build-up within the exhaust system. The best cleaners will succeed each and every time but may struggle with those with decades of carbon build-up. To avoid getting to this situation, it’s recommended that you use the cleaner 3 to 4 times a year.

Not all catalytic converter cleaners will be compatible with your engine. Many are only suitable for gasoline powered engines and not diesel or hybrids.

Below is a list of the best catalytic converter cleaners that clean the entire fuel and exhaust system from a single application.

Cataclean Engine and Catalytic Converter Cleaner

By far the most popular catalytic converter cleaner on the market is the Cataclean formula. It aims to restore and maintain the exhaust and fuel system to improve overall engine performance.

The brand claim that from using this formula, it can potentially lower hydrocarbon emissions by up to 50%.

Other features of the Cataclean 120007 include:

  • Safe for gasoline, diesel, hybrid and flexi fuel vehicles
  • Recommended to use every 3 months
  • Improve engine performance and efficiency
  • Cleans both the engine and exhaust
  • Complies with VOC and OTC regulations
  • 473 ml bottle
  • Made in the USA

The unique formula is designed to break down and remove harmful carbon deposits in just one application. Although it’s not the cheapest catalytic converter cleaner, it certainly provides the best results and reduces emissions by up to 50%.

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CRC 05063 Guaranteed to Pass Formula

Another popular formula is the CRC 05063, which is branded as “Guaranteed to Pass“. CRC are so confident that this catalytic converter cleaner will pass an emissions test that they offer a money back guarantee.

It is a concentrated formula that maximizes the allowable cleaning chemistry in order to provide results in one application.

Other features of the CRC 05063 Emission Test Formula include:

  • Removes carbon from the catalytic converter and fuel injectors
  • Needs to be used every 3,000 miles
  • Suitable for gasoline and ethanol blended fuels
  • Results after usage in a full tank
  • 335 ml concentrated formula

The “Guaranteed to Pass” tagline is a strong statement but the guarantee provides peace of mind that it’ll work. If you have failed your emissions test, the CRC 05033 is the best option to restore performance and reduce emissions.

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OXICAT Catalytic Converter Cleaner

The OXICAT formula is a premium option but the catalytic converter cleaner is designed to clean the entire exhaust system. It is a German made formula that is also designed to clean the oxygen sensors too.

The brand states that it can be used with all fuel types but is only activated once the exhaust reaches optimum working temperature.

Other features of the OXICAT Catalytic Converter Cleaner include:

  • TUV certified and made in Germany
  • Engineered to completely clean the exhaust system
  • Dissolves soot, varnish and carbon residue
  • Use every 3 to 4 months
  • Optimizes engine performance and increase fuel efficiency
  • Complies with the latest environmental requirements
  • Concentrated 250 ml bottle

Overall, the German made OXICAT formula is an expensive option but highly effective. It’s important to note that the exhaust system must be at optimum temperature to get the most from this catalytic converter cleaner.

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Solder-It Catalytic Converter Cleaner

Solder-It is a gas additive that is designed to reduce emissions and remove the dreaded “rotten egg” odor. The brand state that it should be added to a quart full fuel tank and used for 40-60 miles before refilling with the formula.

Other features of the Solder-It (CAT-1) include:

  • Suitable for gasoline engines
  • Desirable deodorizing properties
  • Cleans the oxygen sensor
  • Reputable brand backing the formula
  • Large 473 ml bottle

If your car suffers from the terrible smell of rotten eggs and poor emissions, this is the best option. It is both a cleaner and deodorizer that offers great value for money and will not disappoint.

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MotorPower Catalytic Converter Cleaner

The MotorPower formula is designed for diesel, gasoline and hybrid vehicles with effective results. The brand recommend that you use this cleaner every 3 to 4 months with the ratio of 250 ml to every 15 gallons of fuel.

When used regularly, the brand state that it increases fuel efficiency, performance and proper functioning of the catalytic converter.

Other features of the MotorPower Cleaner include:

  • Dissolves dirt, varnish, rubber and carbon residue
  • Complies to latest environmental requirements
  • Proven results by professionals
  • Works whilst the car is running
  • Protects against renewed contamination
  • 250 ml bottle

Overall, it is a high performing catalytic converter cleaner that is OEM approved. It dissolves harmful compounds found in the entire exhaust system with a single bottle treating up to 60 liters of fuel.

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Hi-Gear HG3270s Catalytic Converter Cleaner

The Hi-Gear formula is designed to clean the fuel system, injectors, combustion chamber, pistons and valves. The brand state they work closely with top additive manufacturers and OEM brands to gain access to the latest cleaning technology.

As well as cleaning the catalytic converter, the formula is also designed to eliminate the rotten egg smell.

Other features of the Hi-Gear HG3270s include:

  • Suitable for gasoline engines only
  • Removes toxic gases and CO2 emissions
  • Restores lost horsepower
  • Increases fuel efficiency
  • One can treats 20 gallons
  • 444 ml bottle

Hi-Gear have produced multiple catalytic converter cleaners but the HG3270s is the new and improved formula. Overall, it is an excellent all-round cleaner that offers great value for money and won’t disappoint.

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Catalytic Converter Cleaner Buying Guide

The use of a catalytic converter cleaner could be the difference between passing or failing an emissions test. They are a fraction of the price of a new catalytic converter and the cleaner gets to work with a full tank of fuel.

When browsing through the various cleaners available, you want to ensure they are compatible. The manufacturers will state whether they are suitable for your engine or fuel type on the bottle.

To help you make an informed buying decision, we have produced the below guide regarding catalytic converter cleaners.

catalytic converter cleaner

Why You Need a Cleaner

As the fuel is ignited within the combustion chamber, gases are sent through the exhaust system. However, before these harmful gases are passed into the air, they must pass through the catalytic converter. This reduces the toxicity levels but the downside is that they need to be cleaned to continue to work.

Failing to clean the catalytic converter will result in increased emissions and a reduction in performance. The build-up of carbon deposits will continue to increase the longer you leave it and they can become even more difficult to clean.

How To Use a Cleaner

Using a catalytic converter cleaner is quick and easy to do. To begin, you will need to pour the entire bottle into the tank. Some manufacturers will state a specific ratio, which needs to be strictly followed for the best results.

Once the tank is filled with the appropriate amount of fuel, you will then need to drive it for at least 50 miles. The cleaning process needs the catalytic converter to be at optimum working temperature to be effective.

If a check engine light remains after using a cleaner, you may require an automotive diagnostic scanner. This will allow you to read any code that are stored and clear them. If it still remains, you may have further faults that a cleaner cannot fix.

It is recommended that you use the cleaner 3 to 4 times a year for maximum protection from carbon deposits building up.

Instant Benefits

The main reason for using a catalytic converter cleaner is to reduce the emissions. However, they also provide a range of additional benefits that include:

  • Performance increase
  • Smoother acceleration
  • Improved fuel efficiency
  • Elimination of the “rotten egg” smell
  • Improves the operation of the oxygen sensor
  • Saves money without the need of purchasing a new catalytic converter

Considering that they are relatively cheap to purchase and provide multiple benefits, they are a worth using on a regular basis.

How Does it Work?

The cleaner is poured into the fuel tank and once burnt, it combines with the exhaust gases. The combination of gases is then passed through the exhaust system and into the catalytic converter.

It then gets to work and dissolves all the dirt, varnish, rubber and carbon residue. Regular usage of a cleaner will help keep the catalytic converter clean and helps to prevent the build up of carbon deposits.

It is worth noting that you could have the best catalytic converter cleaner available but if the catalytic converter is damaged, the cleaner won’t make a difference.


Not every catalytic converter cleaner available will be suitable for all engines. Some are suited to just gasoline engines whereas other may be for only 2 or 4 stroke engines. The manufacturer will clearly state on the bottle the types of engines that the cleaner is compatible with.


Trying to pass an emissions test with a blocked catalytic converter is not going to end well. However, with the latest cleaning technology, using a quality catalytic converter cleaner can help you pass with many brands providing guarantees.

All of our recommendations within this article are suited to a range of fuel types and budgets. There are hundreds of formulas that guarantee a pass but there may be other factors that is stopping your car from passing.

procarreviews author

Written By Dan

About the Author

Dan is an automotive journalist and owner of over 10 cars ranging from supercars, tuned cars, classics and your good old beater cars. He always likes to get his hands dirty with nut and bolt restorations or detailing sessions using the best products on the market.

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