The Best Catalytic Converter Cleaner For Petrol & Diesel Engines

By on 9 September 2020 / Leave a comment Updated on: 17th February 2021

Two important components within your vehicles exhaust system. Firstly, the catalytic converter. This is an emission reducing device, that aims to prevent harmful gasses from the engines combustion cycle from being emitted into the atmosphere. The O2 sensor meanwhile detects the levels of oxygen being expelled from the engine and uses this information to adjust fuelling and other engine parameters to ensure efficient running.

Over time, as a result of combustion, gasses filled with particulates and other debris are passed into the exhaust system and on to the filters of the catalytic converter and the O2 sensor. This debris is deposited on both items, reducing their efficiency, affecting readings passed to the cars computer and causing blockages over long periods.

The Benefits of Implementing a Catalytic Converter & O2 Sensor Cleaner

Debris build up and poor readings sent by the O2 sensor, can cause poor running and huge decreases in fuel economy. O2 sensor readings are continuously monitored by your cars computer to help adjust that amount of fuel being supplied. Readings affected by dirt and build-up on the sensor can therefore cause your car to over fuel or lean out, neither is efficient or good for the life of your engine internals.

Freeing any clogs within the catalytic converter allows for better flow of exhaust gasses, letting your engine breathe properly and work more efficiently overall. Restoring lost performance and increasing fuel economy are just a couple of the benefits found from using one of the cleaners listed below to clean your cars vital exhaust components.

The Best Catalytic Converter & O2 Sensor Cleaners for Petrol Vehicles

Cataclean Petrol

cataclean petrol

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Our first product is from Cataclean, a brand that dedicates itself wholly to providing vehicle cleaning additive solutions. Their petrol offering promises to give a full clean right from the fuel tank to the exhaust system, with particular attention paid to clearing contaminant build up from the catalytic convertor and oxygen sensors.

Clearing any clogged debris within the catalytic convertor will enable your engine to run more efficiently. This will result in improved performance, reduced fuel consumption and minimisation of unwanted harmful exhaust emissions. This could be the ideal solution if your car has recently failed an MOT due to increased emissions levels.

Cataclean works with all petrol vehicles by simply pouring into the fuel filler nozzle. From here it will rapidly spread through the fuel system and into the engine where, after combustion, it will make its way into the exhaust system to clear soot and carbon build-ups from the catalytic convertor and oxygen sensors. Simply apply the product every 3000 miles.


  • Brand dedicated to additive cleaning formulas
  • Clears full fuel system of unwanted build-ups
  • More efficient running from your engine
  • Improves performance and fuel economy
  • Reduces unwanted, harmful emissions


  • Requires full bottle application every 3000 miles

JLM Petrol Catalytic Converter Cleaner

jlm catalytic converter cleaner petrol

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Next up, is the European brand JLM lubricants. Known for their performance enhancing products, JLM also offers an exhaust cleaning solution that promises to rapidly restore full functionality to your catalytic convertor and get those pesky emissions back under control.

A fully flowing exhaust system will restore lost performance to your vehicle, while also reducing fuel consumption. Long term reliability for your engine will also be improved as removal of deposits will not only reduce the likelihood of sticking valves, but will increase corrosion resistance as the moisture trapped by deposits is released.

Cleaning the fuel system on its path through to the catalytic convertor, JLM’s cleaning additive should also help prevent fouling of the exhaust components in the future. Like competitors, the entire bottles contents should be added to your fuel tank (with at least 25 litres of fuel) and reapplied roughly every 3000 miles.


  • Well trusted additive manufacturer
  • Clears catalytic convertor and oxygen sensors of unwanted build-ups
  • Reduces harmful emissions
  • Restores lost performance and fuel economy
  • Corrosion resistance benefits


  • Most expensive petrol offering
  • Requires full bottle application every 3000 miles

Wynns Catalytic Converter & Lambda Cleaner

wynns catalytic converter and lambda cleaner

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Wynns product is one of the better known in the UK and for good reason. Wynns upholds a reputation for good quality products that perform as intended, especially important with a product such as this, where you cannot physically see the solution making a difference.

The catalytic converter and lambda cleaner promises to clear the exhaust system of unwanted debris that could be causing poor running and warning lights on your dashboard. This will enable the catalytic converter to run at maximum efficiency, while also ensuring correct reading from your O2 sensors. Especially useful in vehicles driven often in town/ city driving where the exhaust flow does not reach the temperature required to deter debris build-up.

Implementing the cleaner promises to reduce emissions and restore lost performance to your car. It requires no dismantling or vehicle knowledge, is simply added into your fuel tank with your next fuel fill. Product is suitable for all petrol and petrol hybrid vehicles.


  • Well trusted brand
  • Restores fuel economy
  • Cleans sensors for accurate readings
  • Restores lost performance
  • Cheapest option here


  • Use entire bottle in one application

The Best Catalytic Converter & O2 Sensor Cleaners for Diesel Vehicles

Cataclean Diesel

cataclean diesel

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The first of our diesel offerings comes from Cataclean, with similar principles and aims as their petrol catalytic convertor cleaner. Their product is specifically designed to give a full clean from the tank through to the exhaust pipe, removing dirt that could cause future issues while clearing the catalytic convertor and oxygen sensors of current carbon and soot contamination.

The major advantage of the treatment is a reduction in emissions, up to 60%, which is particularly useful for an MOT, something many cars fail these days due to increased exhaust emissions. Usage will also result in an improved level of fuel economy and restoration of lost performance, thanks to proper exhaust flow.

Simply apply into the fuel tank every 3000 miles (or every 3 months) for long-lasting protection and optimum running. The solution is suitable for all diesel vehicles, whilst having the added benefit of clearing the diesel particulate filter and protecting it from future issues too.


  • Clears deposits from catalytic convertor, oxygen sensors and DPF
  • Huge reduction in emissions
  • Restores lost performance
  • Additionally, cleans and clears fuel system


  • Requires full bottle application every 3000 miles

JLM Diesel Catalytic Converter Cleaner

jlm catalytic converter cleaner diesel

Check the latest price on Amazon

Not to be outdone, JLM lubricants also offers a diesel variant for their catalytic converter and exhaust cleaner. Their unique blend promises cleaning benefits (as with their petrol product), while also acting as a cetane booster to improve fuel properties and optimise engine performance.

As the additive passes through the engine and into the exhaust system it will remove built-up debris from the catalytic converter, oxygen sensors and diesel particulate filter. This will result in the restoration of lost performance, possibly exceeding the levels the car previously attained due to the added cetane booster in JLM’s product. Expect a big drop in emissions and a big jump in fuel economy.

The product is simply added to a tank of diesel fuel every 5000 miles, while being compatible with all modern diesel vehicles and being particularly useful for those that have diesel particulate filters fitted to reduce emissions.


  • Clears debris from fuel system
  • Restores lost performance
  • Big drop in exhaust emissions
  • Only requires full bottle application every 5000 miles
  • Integrated cetane booster


  • More expensive than Cataclean product

Oxicat Oxygen Sensor and Catalytic Converter Cleaner

oxicat o2 sensor catalytic converter cleaner

Check the latest price on Amazon

Our final offering is from Oxicat, a German brand promising to help motorists pass the increasingly stringent emissions tests. To enable this, the formula is designed to clean your catalytic converter thoroughly, enabling proper function and lower emissions as a result. This product is suitable for both petrol and diesel vehicles, though we recommend using on diesel vehicles, due to the design of the additive and the strength of its formula.

The additive will clear all parts of the exhaust (including the DPF) allowing proper flow and efficient running, giving your vehicle restored performance and improved fuel economy. Clearing the oxygen sensors will prevent incorrect readings that lead to patchy running and uneven idling.

The TUV certification (German government vehicle standards) shows that this product is highly tested and proven to be safe for use in modern vehicles while adhering to modern emissions and safety standards. This a unique selling point in the market. Simply add to a full tank of fuel every 3-4 months for continued results and squeaky-clean exhaust internal parts.


  • Vastly reduces dangerous emissions
  • Suitable for petrol and diesel vehicles
  • High strength additive
  • Restores performance and fuel economy
  • TUV certified, safe to use for all vehicles


  • Most expensive product listed

In Conclusion

Neglecting your exhaust system may result in more than just poor running. Modern vehicles are particularly sensitive to their sensor inputs, meaning an O2 sensor that is covered in dirt or debris and giving poor readings can cause warning lights on your dashboard. The resultant poor fuelling can even cause major breakdowns and associated bills. Blocked catalytic converters are no easier to deal with, if left for long periods catalytic converters can be damaged and may even need to be replaced, which will set you back hundreds, if not thousands of pounds.

Using the products above is an easy solution, requires no dismantling of your cars exhaust system and does not need professional assistance in order to reap the benefits. Eliminating the potential issues can give you peace of mind that your vehicle will continue to work flawlessly, without worry of poor performance, reduced fuel economy or reliability woes. Prevent the issues before they arise, get your car running at maximum efficiency for the long term.

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Jack Gill

Car journalist and fully qualified mechanical engineer, Czok’s newest contributor and long-time automotive writer. Lifetime passion for all things automotive, from new supercars to rusty old hatchbacks. If I’m not behind the wheel, I’m likely under the bonnet or browsing the classifieds. Having spent over 5 years in the automotive industry and under the bonnet of my own car at home, I want to share the knowledge and learning that I have gained, with others without the time to study or the expertise, who just want their car to get them from A to B every day. We aren’t all interested in trawling through endless internet pages and forums. I aim to gather all the information up and roll it into a quick summarised format, to give only the information you really need.

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