by Joshua Thomas
The catalytic converter is one of the most important components in your vehicle's emissions control system. Over time, carbon deposits, fuel residue, and combustion by-products accumulate on the converter's honeycomb substrate, reducing its ability to convert harmful exhaust gases into less toxic compounds. The result is degraded emissions performance, potential check engine lights, and — in states with mandatory emissions testing — a failed inspection.
Catalytic converter cleaners are fuel additives designed to dissolve these deposits and restore converter efficiency without the need for costly replacement. When used regularly as part of a maintenance schedule, they can extend converter life significantly. When used before an emissions test, they can help borderline vehicles achieve passing readings by burning off the accumulated carbon that causes elevated HC, CO, and NOx measurements.
With a range of products on the market targeting different vehicle types and use cases, choosing the right cleaner matters. We have researched and reviewed the top options to bring you this updated list of the 6 best catalytic converter cleaners of 2026.
Our top overall pick is Cataclean 120007 Fuel and Exhaust System Cleaner. It stands out from the competition by treating the entire fuel and exhaust system — not just the catalytic converter — in a single pour. Its compatibility with gasoline, diesel, and hybrid vehicles makes it the most versatile choice on our list, and it is trusted by professional mechanics worldwide.
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Cataclean 120007 is the gold standard in catalytic converter cleaners, and it earns that reputation through a genuinely effective formula that works across petrol, diesel, and hybrid vehicles. Developed in the UK and widely trusted by professional mechanics, Cataclean cleans not just the catalytic converter but also the entire fuel and exhaust system in a single treatment.
The formula works by removing carbon deposits and other combustion by-products from the fuel injectors, combustion chamber, oxygen sensors, and catalytic converter itself. When these deposits accumulate, they reduce combustion efficiency and cause the converter to work harder to reduce pollutants — Cataclean dissolves them and restores clean operation. Most users report a noticeable improvement in throttle response and fuel economy after treatment.
Using Cataclean is straightforward: pour the entire bottle into a fuel tank that is approximately one-quarter full, then drive normally for at least 15 minutes of highway or motorway driving to allow the formula to cycle through the system at elevated temperatures. A single 16.7 oz bottle treats up to 15 gallons of fuel.
It is safe for oxygen sensors and all catalytic converter types, and it is compatible with ethanol-blended fuels. Cataclean is certified for use in the United States and meets EPA requirements. Regular use — once per quarter — keeps the system clean and can help maintain passing emissions test readings.
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Solder-It CAT-1 is a professional-grade catalytic converter cleaner formulated specifically to restore converter efficiency and reduce exhaust emissions in gasoline-powered vehicles. It has built a strong reputation among mechanics and DIY enthusiasts for its consistent, reliable results at a competitive price point.
The CAT-1 formula contains a concentrated blend of detergents and combustion improvers that target the carbon deposits and fuel residue that clog the catalytic converter's honeycomb substrate over time. By dissolving these deposits, it allows the converter to operate at full efficiency, reducing harmful emissions and restoring proper exhaust flow. Many users report the check engine light clearing after treatment when it was triggered by a P0420 converter efficiency code.
Application is simple — pour the full 16 oz bottle into a tank with approximately a quarter tank of fuel, then drive for 20–30 minutes at varying speeds to ensure thorough distribution. The formula is safe for oxygen sensors, fuel injectors, and catalytic converters, and it leaves no harmful residue after combustion.
The CAT-1 is formulated specifically for gasoline engines, so diesel vehicle owners should look elsewhere. One treatment per quarter is the standard maintenance recommendation, though a second treatment may be needed for heavily fouled systems.
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Hi-Gear HG3270s is a well-established catalytic converter cleaner that has earned consistently strong reviews for its ability to reduce exhaust emissions and restore converter performance in gasoline vehicles. Hi-Gear is a trusted name in automotive chemical maintenance with a broad product line used by professional mechanics worldwide.
The HG3270s formula is engineered to dissolve the carbon build-up and combustion by-products that accumulate on the converter substrate, oxygen sensors, and exhaust passages over time. Regular accumulation of these deposits reduces converter efficiency and can trigger diagnostic trouble codes related to emissions performance. Hi-Gear's formula works at combustion temperatures to break down these deposits during normal driving.
The 15 oz bottle is poured directly into the fuel tank before adding gasoline, with the recommendation to treat a tank that is between one-quarter and one-third full. A 15–30 minute drive at moderate to high engine speeds is sufficient to cycle the formula through the system fully. Hi-Gear recommends treating every 3,000 miles as part of a regular maintenance schedule.
User feedback consistently notes a reduction in exhaust smell and improved throttle response after treatment. The formula is oxygen-sensor safe and compatible with all types of catalytic converters. It is a particularly cost-effective choice for regular preventive maintenance.
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Motorkote MK-CAT-16-06 is a dual-fuel catalytic converter cleaner that works in both gasoline and diesel engines, making it one of the more versatile options on this list. Motorkote is best known for its engine friction reducers, and that same chemistry philosophy carries over into their emissions treatment formula.
The MK-CAT-16-06 formula targets the carbon deposits and hydrocarbon build-up that reduce catalytic converter efficiency over time. It also addresses fuel injector deposits and combustion chamber residue, providing a more comprehensive fuel system clean alongside the converter treatment. Users report improvements in fuel economy and smoother idle as secondary benefits to the primary emissions-reduction effect.
The 16 oz bottle treats tanks up to 21 gallons, making it suitable for larger-displacement trucks and SUVs that use more fuel per fill-up. Application is straightforward — add the entire bottle to a low tank before filling up, then drive normally. Motorkote recommends treatment every 3,000 to 5,000 miles depending on driving conditions.
While effective as a maintenance product, the MK-CAT-16-06 may require multiple treatments for severely fouled converters showing active trouble codes. Its compatibility with both fuel types makes it particularly attractive for households with both gas and diesel vehicles.
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CRC 05063 Guaranteed to Pass is perhaps the most boldly named product on this list — and it largely delivers on that promise. Designed specifically to help vehicles meet tailpipe emissions test standards, this formula is the go-to choice for car owners facing an upcoming state emissions inspection with borderline exhaust readings.
The CRC formula works by rapidly burning off the hydrocarbon deposits that cause elevated HC, CO, and NOx emissions readings at the test station. Unlike a standard maintenance cleaner, CRC 05063 is optimized for quick, intensive action — it is designed to be used one to two days before an emissions test, not as a long-term maintenance product. Many users report successfully passing inspections they had previously failed after using this formula as directed.
The 12 oz bottle is added to the fuel tank before a fill-up, and the vehicle should be driven for at least 15–20 minutes of sustained highway driving to activate the formula fully. CRC recommends testing within 100 miles of treatment for best results. The formula is safe for oxygen sensors and all catalytic converter types.
It is important to note that while CRC 05063 can effectively reduce borderline emissions, it is not a substitute for mechanical repairs in cases where the converter or engine components are failing. If your vehicle is significantly out of tolerance, professional diagnosis is necessary. CRC backs this product with a satisfaction guarantee.
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Rislone Cat Complete is a premium all-in-one fuel, exhaust, and emissions system cleaner that goes beyond just treating the catalytic converter. It is formulated to address the complete emissions chain — from the fuel injectors and combustion chamber through the O2 sensors and converter substrate — making it one of the most comprehensive treatments on this list.
The Cat Complete formula is compatible with gasoline, diesel, and flex-fuel vehicles, which is a notable advantage for drivers of E85-capable or bio-diesel vehicles. The 16.9 oz bottle provides a generous treat volume of up to 20 gallons, and the formula is safe for turbocharged engines, direct injection systems, and all aftermarket or OEM catalytic converters.
Rislone's formula is particularly effective at addressing the P0420 and P0430 catalytic converter efficiency trouble codes that are commonly triggered by carbon accumulation rather than physical converter failure. By restoring converter efficiency, it can clear these codes and restore normal emissions system operation. Many users report improved fuel economy and throttle response as additional benefits.
For best results, Rislone recommends adding the formula to a low tank before filling up and driving for at least 50 miles. Rislone is a well-established American automotive chemical brand with a long history of quality and a strong consumer satisfaction guarantee behind their products.
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Not every catalytic converter cleaner is the right fit for every situation. Whether you are looking for a regular maintenance additive, a pre-emissions-test treatment, or a solution for a check engine light, understanding the key factors will help you make the right choice.
This is the first and most critical specification to check. Most catalytic converter cleaners are formulated for gasoline engines only. If you drive a diesel vehicle, a flex-fuel vehicle, or a hybrid, you need to verify the product explicitly supports your fuel type before purchasing. Cataclean and Rislone Cat Complete are among the few products that support multiple fuel types, making them the safer choice for mixed-fleet households or drivers who are unsure of their exact fuel specification.
There are two primary use cases for catalytic converter cleaners. The first is regular preventive maintenance — using a cleaner every 3,000 to 5,000 miles to prevent carbon build-up before it becomes a problem. The second is remedial use — treating a vehicle before an emissions inspection or after a check engine light related to converter efficiency codes (P0420, P0430) appears. Products like CRC 05063 are specifically optimized for the pre-test scenario and work fastest, while products like Cataclean and Hi-Gear HG3270s are better suited as ongoing maintenance treatments.
Catalytic converter cleaners are typically sold in single-use bottles sized to treat one full tank of fuel. Most treat between 15 and 21 gallons. If you drive a truck, van, or SUV with a larger fuel tank, verify that the product's treat volume matches your tank capacity. Treating an undersized amount of fuel with a full bottle concentrates the formula, which is generally harmless, but treating too large a tank with too small a bottle may reduce effectiveness.
Basic catalytic converter cleaners focus specifically on dissolving deposits on the converter substrate. More comprehensive formulas — like Cataclean and Rislone Cat Complete — clean the entire fuel and exhaust system, including fuel injectors, combustion chamber, oxygen sensors, and EGR components. If your vehicle is showing symptoms beyond just emissions issues, such as rough idle, poor fuel economy, or hesitation, a full-system formula is worth the premium price.
All reputable catalytic converter cleaners are formulated to be safe for oxygen sensors and the precious metal catalysts inside the converter. However, it is worth confirming this on the label, especially when using a product for the first time. Using a cleaner that is not O2-sensor safe can damage an expensive component and create new diagnostic trouble codes in addition to the ones you are trying to resolve.
Catalytic converter cleaners are effective at dissolving carbon and combustion deposits, but they cannot repair a physically damaged or thermally degraded converter. If your vehicle has been running rich for an extended period, has suffered overheating, or has a converter substrate that is physically broken or melted, no chemical treatment will restore it. In those cases, a professional inspection and converter replacement is the only reliable fix. Use a scanner to check the specific trouble codes before deciding between a chemical treatment and a mechanical repair.
Cataclean 120007 Fuel and Exhaust System Cleaner - Walmart Link
Solder-It CAT-1 Catalytic Converter Cleaner - Walmart Link
Hi-Gear HG3270s Catalytic Converter Cleaner - Walmart Link
Motorkote MK-CAT-16-06 Catalytic Converter Cleaner - Walmart Link
CRC 05063 Guaranteed to Pass Emissions Test Formula - Walmart Link
Rislone Cat Complete Fuel, Exhaust and Emissions System Cleaner - Walmart Link
Cataclean 120007 Fuel and Exhaust System Cleaner - eBay Link
Solder-It CAT-1 Catalytic Converter Cleaner - eBay Link
Hi-Gear HG3270s Catalytic Converter Cleaner - eBay Link
Motorkote MK-CAT-16-06 Catalytic Converter Cleaner - eBay Link
CRC 05063 Guaranteed to Pass Emissions Test Formula - eBay Link
Rislone Cat Complete Fuel, Exhaust and Emissions System Cleaner - eBay Link
Catalytic converter cleaners are one of the most cost-effective maintenance products available for modern vehicles. For a fraction of the cost of a converter replacement, a quality cleaner can dissolve the carbon deposits that degrade converter efficiency and trigger emissions-related check engine lights.
Our top overall pick, Cataclean 120007, earns its place at the top of the list through its broad fuel-type compatibility, comprehensive system cleaning action, and proven real-world results across a wide range of vehicles. For a purpose-built pre-emissions-test solution, CRC 05063 is the most targeted and fastest-acting option available.
For drivers looking for excellent value in a reliable maintenance cleaner, Hi-Gear HG3270s and Solder-It CAT-1 both offer consistent performance at accessible price points. For the most comprehensive full-system treatment available, Rislone Cat Complete goes further than most competitors by addressing the entire emissions chain from injectors to tailpipe.
Whichever product you choose from our list, using it on a regular maintenance schedule — every 3,000 to 5,000 miles — is the best strategy for keeping your catalytic converter clean, your emissions in compliance, and your check engine light off.
Yes, catalytic converter cleaners can be effective in many cases, but with an important caveat: they work by dissolving carbon deposits and combustion residue that have accumulated on the converter substrate over time. If the converter is fouled by deposits, a quality cleaner can restore efficiency and clear related diagnostic codes. However, if the converter is physically damaged, has a melted or broken substrate, or has been contaminated by coolant or oil, no chemical treatment will fix it and replacement is required.
For preventive maintenance, most manufacturers recommend using a catalytic converter cleaner every 3,000 to 5,000 miles, or roughly every other oil change interval. If your vehicle has just triggered a P0420 or P0430 emissions code, a treatment cycle of two applications spaced 500 miles apart is often recommended before performing a drive cycle for the diagnostic monitor to reset. Regular maintenance treatments prevent the heavy build-up that requires more intensive remedial treatment later.
It depends on the root cause. If the P0420 code (or P0430 for Bank 2) is triggered by carbon deposit build-up reducing converter efficiency, a quality cleaner like Cataclean or Rislone Cat Complete can dissolve those deposits, restore converter performance, and allow the code to clear after a complete OBD-II drive cycle. However, if the code is triggered by an aging or physically degraded converter that is genuinely below efficiency threshold, or by an upstream engine issue like running rich or burning oil, a cleaner will not provide a permanent fix.
Yes, all reputable catalytic converter cleaners are formulated to be safe for modern vehicle systems, including oxygen sensors, direct injection systems, turbocharged engines, and all OEM and aftermarket catalytic converters. Always verify the product label confirms compatibility with your specific fuel type and engine technology. Products like Cataclean and Rislone Cat Complete explicitly note compatibility with turbocharged and GDI (gasoline direct injection) engines.
Yes, and this is actually the recommended approach for pre-test use. Add the cleaner to a low tank, fill up with fuel, and then complete 15–30 minutes of highway driving to ensure the formula cycles through the system at operating temperature. CRC 05063 Guaranteed to Pass is specifically designed for this use case. Most manufacturers recommend testing within 100 miles of treatment for best results. Note that OBD-II readiness monitors must also be set — drive normally for at least 50–100 miles after the cleaner treatment to allow all monitors to complete.
Fuel injector cleaners are formulated primarily to clean deposits from fuel injector tips, intake valves, and combustion chambers. They focus on the fuel delivery side of the engine. Catalytic converter cleaners are formulated to work further downstream in the exhaust system, targeting the converter substrate and oxygen sensors. Many premium products — including Cataclean and Rislone Cat Complete — combine both functions in a single treatment, cleaning the entire system from the fuel injectors through the exhaust outlet.
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About Joshua Thomas
Joshua Thomas just simply loves cars and willing to work on them whenever there's chance... sometimes for free.
He started CarCareTotal back in 2017 from the advices of total strangers who witnessed his amazing skills in car repairs here and there.
His goal with this creation is to help car owners better learn how to maintain and repair their cars; as such, the site would cover alot of areas: troubleshooting, product recommendations, tips & tricks.
Joshua received Bachelor of Science in Mechanical Engineering at San Diego State University.
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