Best Catalytic Converter Cleaners: Clean Engines, Smooth Rides

Keep your engine high-performance ready with regular catalytic converter cleaning

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BY Katherine Rother / LAST UPDATED ON May 13, 2019

A car or truck's catalytic converter filters out toxic chemicals and compounds such as carbon monoxide from exhaust emissions and converts them to gases that are not as harmful. During the process, the catalytic converter can clog up, and it requires regular cleaning to properly function. That's why people use catalytic converter cleaners. In our guide, you’ll learn everything you need to know to find the best catalytic converter cleaner for your needs.

Best Overall
Chevron Techron Concentrate Plus Fuel System Cleaner

One of the top products on the market, this catalytic converter cleaner is concentrated to deliver super-charged results.

  • Cleans, restores, and protects the entire fuel system
  • Helps restore lost power and acceleration
  • Improves fuel efficiency
  • Smoothes idling and improved cold start performance
  • Inconvenient packaging
  • Foil that seals the cap is difficult to remove, leading to
Best Overall
Chevron Techron Concentrate Plus Fuel System Cleaner
Best Value
OXICAT Oxygen Sensor & Catalytic Converter Cleaner

This German-made formula uses decarbonizing technology to clean a vehicle's entire exhaust system. It's compatible with both gas and diesel vehicles.

  • Dissolves soot and carbon deposits and prevents noxious residue from building up
  • Easy to use and maintains engine performance
  • Won’t repair a damaged exhaust system, and it doesn't cure all problems
  • You may need more than one can
Best Value
OXICAT Oxygen Sensor & Catalytic Converter Cleaner
Honorable Mention
Red Line Complete SI-1 Fuel System Cleaner

A concentrated fuel system cleaner, this restores engine efficiency with just one treatment in new and old cars.

  • Formulation made for continual use
  • Synthetic lubrication included in the formulation to help your engine run more smoothly
  • Reduces carbon buildup in all engine parts
  • Helps clear up engine sounds
  • Packaging qualm: The nozzle on the bottle is too short to properly fit into some gas tanks, which can lead to spills
Honorable Mention
Red Line Complete SI-1 Fuel System Cleaner

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All of our reviews are based on market research, expert input, or practical experience with most products we include. This way, we offer genuine, accurate guides to help you find the best picks.

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Benefits of Catalytic Converter Cleaner

  • Lower emission levels. Modern catalytic converters do pretty well to keep the number of harmful gases emitted from the car’s engine to a minimum. Adding a catalytic converter cleaner to the mix reduces the engine’s emission levels even further.
  • Better engine performance. Have you noticed less performance from your engine? A gunked up catalytic converter may be to blame. Using a catalytic converter cleaner regularly will help clean the fuel injection system as well as the cylinders, improving overall performance while cutting down on fuel consumption.
  • Save money. Better engine performance has another benefit: it saves you money, thanks to lower maintenance and fuel costs. On top of that, you won’t have to shell out the big bucks to change your catalytic converter.
  • Reduce bad smells. Some cars develop an icky smell over time caused by build-up in the catalytic converter. If your car has the signature rotten egg smell, a catalytic converter cleaner can help.
  • Protect your engine. Regularly cleaning your catalytic converter has another big benefit: it’ll help protect your engine from damage. Proper fuel and exhaust flow will keep that engine running cleaner, smoother, and better, which will also cut down on maintenance costs.
  • Pass emission tests. If you’ve got an older vehicle and are up for an emissions test, a catalytic converter cleaning treatment can help. The formulation knocks old gunk, grime, and other carbon-based build-ups out of the fuel system, leading to cleaner emissions.

Top Brands

Red Line Oil

Headquartered in Benicia, Calif., Red Line Oil has been around for over 40 years. With roots in the racing industry, Red Line later expanded into the mainstream markets as manufacturers of high-quality engine lubricants. Since then, the company has expanded again into making a number of different automotive fluids, with the Complete SI-1 Fuel System Cleaner being among its most popular products.


Founded in 1879, Chevron is among the big names in the automotive and oil sectors. With headquarters in San Ramon, Calif., Chevron has been continuing to make high-quality automotive products, among which we find the most popular catalytic converter cleaner on the market, the Techron Concentrate Plus Fuel System Cleaner.

Royal Purple

Based in Porter, Texas, this automotive oil company prides itself in making high-quality engine oils and lubricants. With more than 200 years of collective experience in making high-performance lubricants and other automotive fluids, Royal Purple is a name you can trust. The company’s most popular product is the Max-Clean Fuel System Cleaner.

Catalytic Converter Cleaner Pricing

  • Under $10: Catalytic converter cleaner at this low price point is usually a budget option. You won’t get as good cleaning as from a mid-range or high-end brand, and you might accidentally get stuck with a knock-off that can do more harm than good.
  • $10 - $20: At this price point, you’re getting a good quality product that will get the job done. You’ll find a number of slightly different formulations that end up doing most of the same thing. Keep in mind that a diesel or hybrid car will need a different formulation, many of which can be found at the upper end of this price range.
  • Over $20: The high-end of catalytic converter cleaners consists of big name brands and multipacks. If you’re paying more than $20 for a single bottle, you could already be paying too much, unless it’s a specialty formulation.

Key Features

Engine Compatibility

For regular, gasoline-powered engines, almost all catalytic converter cleaning treatments will work with your vehicle. If you happen to drive a diesel or hybrid car, however, check the engine compatibility of the cleaner you’re considering. In most cases, a more premium blend is needed for this type of specialized engine.

Full System Cleaning

The best formulations are capable of cleaning the entire exhaust system, not just the catalytic converter. Since every part of the exhaust system is integral to how well the overall system functions, your catalytic converter cleaner should be able to give the whole thing a good flush. That will keep everything working in unison.

Multipack Options

Although the catalytic converter cleaner isn’t all that expensive, you’ll still want to make use of a great deal. This is where multipack options come in. They’re especially useful as you’ll need catalytic converter cleaner as a regular part of your car maintenance routine, saving you money in the long run.

Other Considerations

  • Additives: Some catalytic converter cleaners include additional detergent additives that you don’t need in an effort to sell at a higher price point. If you’ve got a regular gas-powered car, you don’t need anything fancy to do the job right.
  • Bottle Size: Although not the most critical consideration, it’s still an important one. Catalytic converter cleaner comes in a number of bottle sizes, with 16 ounces being the most common. Anything bigger will be a waste, as the opened bottle will start to lose potency over time.
  • Formulation: The labeling of catalytic converter cleaner can be a little confusing since there are a number of look-alike products out there. Keep in mind that fuel treatments and stabilizers are not necessarily catalytic converter cleaners.

Best Catalytic Converter Cleaner Reviews & Recommendations 2021

Best Overall
Chevron Techron Concentrate Plus Fuel System Cleaner

One of the most popular products on the market, the Chevron Techron catalytic converter cleaner works on multiple levels. It cleans, restores, and protects the entire fuel system, including the injectors, carburetors, intake valves, and combustion chambers. Through its unique formula, it restores lost power and acceleration and helps boost fuel economy. If you’re having trouble with the fuel gauge sensor, this product can help reset it.

This product is particularly helpful on older vehicles. It reduces rough idle and engine surge as well as spark plug fouling, helping your engine run more smoothly in the process. If you live in colder areas, you’ll definitely benefit from the improved cold start performance and fuel stability this product provides. It’s suitable for gasoline engines, including motorcycles, dirt bikes, boats, and lawnmowers.

Overall, this is one of the best catalytic converter cleaners available, as it removes carbon build-up from the entire fuel system and the engine. Our one issue with this product is the packaging. The foil that seals the cap is really hard to remove, making it a bit of a hassle to use. You also have to be careful not to drop any of the foil into your gas tank as you’re filling in the product.

Best Value
OXICAT Oxygen Sensor & Catalytic Converter Cleaner

If you don't want to spend a lot of money, consider the OXICAT Oxygen Sensor & Catalytic Converter Cleaner. Made in Germany, this cleaner uses decarbonizing technology to clean your vehicle's complete exhaust system as long as you use it on a regular basis. It's designed to dissolve soot and carbon deposits and is safe to use on all gas and diesel vehicles.

In order for OXICAT to work properly, your catalytic converter must reach and sustain its working temperature. It will prevent noxious residue from building up, which can cause the vehicle to fail emissions tests. The formula meets and/or exceeds environmental standards, is TUV certified, and is a good way to maintain performance and engine life. Simply pour it in the gas tank, and it will do the work for you.

However, OXICAT is not designed to repair a damaged exhaust system, and it doesn't work for all problems. You may also need to use more than one can to clean a dirty or partially clogged catalytic converter, which can drive up the cost.

Best for Small Vehicles
Red Line Complete SI-1 Fuel System Cleaner

As a concentrated fuel system cleaner, this Red Line SI-1 is powerful stuff. It cleans to nearly 100-percent efficiency in a single treatment, barring any major carbon build ups. The formula is designed to reduce the need for octane by up to two points and is safe for continual use, making it perfect for regular car maintenance. One small bottle per tank of gas is an effective treatment for cleaning out gunk and grime from your vehicle’s catalytic converter and overall fuel system.

Another great benefit of this product is the synthetic lubricant in the formula, which coats the upper cylinders. This helps your engine run more smoothly. As part of a regular maintenance program, this product helps keep your intake manifold and throttle body free of carbon build-up, reducing wear on the engine’s parts. If you have an older car that has a ping in the engine, this product has been known to help clear that up as well.

Overall, this is a great product that delivers consistent results. The only thing we are disappointed with is the short nozzle tip of the packaging, which can make it a little difficult to fill into some gas tanks. This mostly affects big SUVs and trucks, however, so you should be good to go with smaller vehicles. A funnel can also help keep the pour drip-free.

Best Quick-Dry
Berryman B12 Chemtool Carburetor, Choke, and Throttle Body Cleaner

Featuring 100 percent high-energy solvent technology, the Berryman B12 is a well-engineered fuel system cleaner that’s designed to keep the carburetors, injectors, automatic choke, intake ports, throttle body, and valves clean. It works quickly to disperse moisture in gas engines and to dissolve fuel deposits, including gum and varnish. It also dries fast, leaving behind no deposits.

After the first treatment, you will notice some significant improvements in your vehicle's driving ability and fuel economy. It can also combat issues such as loss of acceleration and rough idle. You can use this product on ATVs, UTVs, street motorcycles, off-road motorcycles, snowmobiles, and marine equipment.

One downside is that it's a very strong formula that can irritate your eyes and skin. Once you open the bottle, you will be hit with strong fumes, so it's safer to keep it away from your face and wear protective gear, including gloves, eye goggles, or a full face mask when handling it. Regardless, the product is safe for catalytic converters and oxygen sensors.

Premium Pick
Star Tron Enzyme Fuel Treatment Concentrate

This is a concentrated fuel treatment formula that’s specially designed for all gas engines and even engines that use ethanol-blended fuel. It uses a unique enzyme technology that works to disperse water from the fuel by splitting it into submicron-sized droplets that can be burned away in normal engine operations. It goes a step further to remove gum and carbon deposits in the fuel, which helps maintain a clean fuel burn for optimal engine performance.

It’s designed to stabilize your system for about two years on a single treatment no matter the season. One fluid ounce can treat up to 16 gallons of gas, so you get great value for the money. If your engine has been sitting idle for months, this catalytic converter cleaner is the best option that will help to get it back on the road with minimal issues. The product can be used in cars, trucks, motorcycles, snowmobiles, ATVs, and outdoor power equipment.

The main drawback of this product is its container. The spout is poorly designed, and it can get messy when pouring the fluid since some of it may run down on the side. Also, the bottle might leak when it tips over even if the cap is tightly screwed on.

Honorable Mention
Royal Purple Max-Clean Fuel System Cleaner and Stabilizer

The Max-Clean Fuel System Cleaner and Stabilizer is a synthetic formula that’s engineered to deeply clean gas and diesel engines, including those that use biofuel or ethanol blends. It also works for both four-cycle and two-cycle engines. It’s an all-purpose cleaner that will remove gum, varnish, and other deposits from the entire fuel system.

Generally, it is estimated that the product will improve fuel economy by about 3.2 percent, increase horsepower by about 2.6 percent, and reduce hydrocarbon emission by about 12 percent. It may not seem like much, but with time you will experience better starts and minimal rough idle. In addition, it prevents oxidation, corrosion, and premature spark plug fouling. If you have an off-season vehicle or one sitting idle in storage, you can use this cleaner to stabilize the fuel so that it can be in top shape when it’s time to take it out on the road.

However, this product might trigger the oxygen sensor since it can cause changes in fuel quality. This may translate into more costs in resetting the oxygen sensor. Another downside is that the bottle might have a few dents upon delivery.

Honorable Mention
Motorkote Catalytic and Exhaust Treatment

The Motorkote Catalytic and Exhaust Treatment comes in a 16-ounce bottle and is designed to protect your catalytic converter and exhaust system from oil poisons. It will improve performance, increase fuel efficiency, protect your converter, and reduce your vehicle's carbon footprint.

The manufacturer recommends using this product when the warning light is activated on your dashboard. Add the entire bottle into 16 gallons of fuel, or use one ounce per gallon. It's designed to reduce phosphorus and zinc retention levels and is safe to use with gasoline engines and all catalytic converters and oxygen sensors. It will clean O2 sensors, lower tailpipe emissions, and help you pass an emissions test. The formula lasts up to six months or 7,000 miles. Users have reported that their vehicles run smoother and idle better after using this product.

However, not all users have noticed a substantial difference after using the Motorkote treatment. Others complain that the "check engine" light comes back on after a short period of time.

Honorable Mention
Sea Foam SF-16 Motor Treatment

Coming as a two pack, Sea Foam is a multipurpose motor treatment that dissolves gum and other fuel deposits in gas and diesel engines. While it won’t directly clean your catalytic converter, it cleans other components of the fuel system, including the fuel injectors, carburetors, and combustion chamber. As a result, toxic emissions will be reduced, the fuel system will run cleaner, and the catalytic converter will be clog-free.

A single treatment can help get eliminate the error codes that pop up on your dashboard. It’s not a harsh detergent and won’t corrode critical parts of your engine. Also, it can help stabilize stored fuel for about two years by resisting evaporation and the formation of fuel deposits.

The condition of the packaging is its most significant downside. You may receive a dented or leaking bottle. Also, it may not be strong enough for cleaning off-road motorcycles or older vehicles.

Honorable Mention
CRC Guaranteed to Pass Emission System Cleaner

Completing our list is a detergent additive that cleans the entire fuel system to reduce toxic emissions. The cleaner dissolves carbon and varnish deposits from the fuel system and, as a result, reduces carbon, hydrocarbon, and nitrogen emissions. It also cleans the emission control components in gas-powered vehicles. This translates to a cleaner and more efficient catalytic converter.

When used every 3,000 miles, this cleaner can improve acceleration by optimizing the throttle response and gradually improving fuel economy. It’s compatible with gas and ethanol-blended fuels, and it will help you pass your emission test.

However, the results may be somewhat mixed for older vehicles with a weaker catalytic converter. There’s no guarantee that it will help you pass an emission test if you have an old or high-mileage vehicle. For these cars or trucks, consider buying a stronger cleaner.


  • As a general rule of thumb, you’ll want to use about one ounce of catalytic converter cleaner to one gallon of fuel. This formula makes it easy to adjust the amount you need for smaller engines, including motorcycles.
  • You don’t need to have a full tank of gas to use a catalytic converter cleaner. The more important step is to use up as much of the tank as possible with the converter cleaner in it to maximize its cleaning potential.
  • Older cars may benefit from more frequent catalytic converter cleaner use because they tend to produce more harmful emissions than newer vehicles.
  • After using catalytic converter cleaner, fill up your gas tank completely and drive about 50 miles on highways and side streets to re-calibrate your onboard computer. This step can help clear up oxygen sensor issues among other things.
  • If you’ve never used a catalytic converter cleaner before, and you’ve already driven thousands of miles, start sooner rather than later with regular catalytic converter maintenance to help reduce the chance of trouble down the line.
Hands of a mechanic visible in the process of changing an old catalytic converter with rusted parts

Help prevent a costly catalytic converter replacement by keeping your fuel system clean and well-maintained


Q. How do I use a catalytic converter cleaner?

A: Using a catalytic converter cleaner is one of the simplest routine maintenance tasks you can perform. One 16-ounce bottle is enough to clean up a couple of thousand miles worth of gunk. Simply pour it into your semi-full gas tank and drive on that tank until it’s almost empty to make sure that most of the chemical cleaner is used up.

Q. Can I use a catalytic converter cleaner to fix a clogged catalytic converter?

A: Unfortunately, catalytic converter cleaner is not a mechanic-in-a-bottle and won’t be the end-all, fix-all to your engine troubles. If your catalytic converter is truly clogged the only way to fix the problem is to replace the converter.

Q. How does a catalytic converter cleaner work?

A: Catalytic converters do their job by filtering out and converting harmful compounds and gases in the exhaust into less harmful ones, like carbon dioxide and nitrogen. In this process, gunk can start accumulating in your catalytic converter, most of which will be carbon. A catalytic converter cleaner is a liquid chemical formulation that runs through your converter, dissolving the build-up via chemical reactions.

Q. How often can I use a catalytic converter cleaner?

A: The catalytic converter is one of the most overlooked car parts, often only getting cleaned after many thousands of miles. To get the best results from both your cleaner and your car, consider cleaning the catalytic converter every 4,000 miles or so.

Q. Do catalytic converter cleaners work in all car makes and models?

A: Catalytic converter cleaners are safe to use with all car makes and models, including older cars. However, if you drive a diesel or hybrid vehicle, make sure the cleaner you buy is compatible with your engine. How well they work depends on a couple of factors, but mainly on how much grime has accumulated within your converter. The more dirt, the fewer results. Make sure to clean your catalytic converter regularly.

Final Thoughts

Our top pick for the best catalytic converter cleaner out there is the Chevron Techron Concentrate Plus Fuel System Cleaner. It delivers consistently great results that help your engine run better.

For a budget-friendly pick, check out the OXICAT Oxygen Sensor & Catalytic Converter Cleaner