What Is a Catalytic Converter Cleaner, and Does It Actually Work?

Liqui Moly Catalytic System Cleaner 6 photos
Photo: Liqui Moly GmbH
Audi A3 Diesel Exhaust SystemReplaced Catalytic ConverterCutout Catalytic ConverterOld Cat vs. NewTailpipe
Part of an ever-growing range of maintenance products, these cleaners are marketed as miracle cures for aging or clogged catalytic converters.
Many of us claim to be environmentally conscious, but few know that the state of our vehicles’ catalytic converters is important for keeping harmful emissions at bay. When they get clogged, the vehicle’s performance must suffer, and more harmful gasses are released into the atmosphere. Since these are expensive parts, some people try to fix them by using these cleaners, but can they unclog and revive them?

Before we answer this question, let’s understand what a catalytic converter is and how it works. An integral part of any ICE-powered vehicle’s exhaust system, it controls and reduces the emissions that come out of the tailpipes.

It uses built-in catalysts to convert toxic hydrocarbons, carbon monoxide, and nitrous oxides into less harmful gasses such as carbon dioxide, nitrogen, and steam.

Cutout Catalytic Converter
Photo: Stahlkocher on Wikimedia Commons
They’re so expensive because they contain precious metals like platinum, palladium, and rhodium, which interact with the hydrocarbons, carbon monoxide, and nitrous oxides released by the engine, converting them into the less harmful gasses mentioned before.

Like many other parts subjected to wear and tear, they have a limited lifespan of approximately 100,000 miles (160,934 km), but the vast majority continue to work properly well beyond that.

They eventually get clogged, and the first sign of this is the presence of a notification or warning light in your vehicle’s dashboard. Other symptoms include increased fuel consumption, loss of power, and dark exhaust smoke coming from the tailpipes accompanied by a smell of sulfur or rotten eggs.

This brings us to the miracle cleaners and treatment products. They are advertised as specially formulated products that remove and prevent carbon buildup inside the cat, clean the entire exhaust system, EGR valve, combustion chamber, and fuel injectors.

Audi A3 Diesel Exhaust System
Photo: Audi AG
Most of them are poured into the gas tank and work their magic as you drive, without modifying the fuel's chemical makeup or damaging any vital components.

But will these products revitalize a clogged cat that should otherwise be replaced? The short answer is no. Using one of these products likely results in ameliorated symptoms, mainly because they contain additives that will clean carbon deposits from your engine’s fuel and exhaust systems. Mind you, they won’t completely eliminate them or magically repair your damaged catalytic converter.

Considering how expensive a new cat is, even on older models, it’s worth giving these products a try before replacing it, right? That’s exactly what companies that manufacture these cleaners capitalize on.

These cleaners might do a good job of mitigating carbon deposits in a fully functional catalytic converter, but don’t expect them to revitalize a damaged one that is well over the 100,000 miles (160,934 km) mark.

Old Cat vs\. New
Photo: CrowzRSA on Wikimedia Commons
My personal experience with a high-quality cleaner yielded absolutely no positive or negative effects, acting more like a placebo, even though I diligently followed the exact steps inscribed on the label.

If you’re willing to give it a try, too, make sure to buy a premium quality one, just to make sure it doesn’t have a negative impact on your engine and exhaust system. These include Mr. Gasket’s Cataclean, which seems to be the most popular out there, Dura Lube’s Severe Catalytic and Exhaust Treatment, Liqui Moly’s Catalytic System Cleaner, or Hi-Gear’s EZ Emissions Pass and Catalytic Converter Cleaner.

But if you really care about your car and - more importantly - the environment, replace your worn catalytic converter.
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About the author: Vlad Radu
Vlad Radu profile photo

Vlad's first car was custom coach built: an exotic he made out of wood, cardboard and a borrowed steering wheel at the age of five. Combining his previous experience in writing and car dealership years, his articles focus in depth on special cars of past and present times.
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