Is Cleaning Catalytic Converter With Lacquer Thinner A Good Idea?

On a nice day, your check engine light was on, and you were wondering if anything happened to your car. Then, the P0420 code was on your OBD2 scanner. Some information on the internet led you to catalytic converter cleaning and guided you using lacquer thinner in gas tank to clean your cat and clear code.

Is cleaning catalytic converter with lacquer thinner a good idea?

This article will answer your question and let you know if lacquer thinner is safe for your cats.

Will Lacquer Thinner Damage Catalytic Converter?

Yes. It is because, while lacquer thinner pops up as a viable option for cleaning a troublesome catalytic converter, it is never safe, especially when you put it into your gas tank. However, to better understand this, it is crucial to understand the composition of lacquer thinner and the potential impact on your car gas tank and related components.

Lacquer thinner is an organic chemical that evaporates quickly in the air. The chemical evaporates more rapidly with increasing temperatures. Lacquer thinner has three main constituents consisting of acetone, methanol, and toluene. However, acetone accounts for the largest share. Therefore, when burned in your engine, acetone, which comprises a dimethyl ketone, turns into water and carbon (IV) oxide, byproducts that can adversely affect specific parts of your car’s engine.

What Happens If I Put Lacquer Thinner In My Gas Tank?

When an oil-based formula evaporates through a catalytic converter, it can cause damage to the converter. The converter can become plugged with lacquer thinner and require replacement. A catalytic converter is a costly part.
The impact of lacquer thinner on your car or engine parts often becomes apparent slowly. It takes a while for the dissolution of parts to reach a point where they leak. It comes about because of the highly aggressive solvents contained in the lacquer thinner. Therefore, it cannot surprise me much to find damages on the fuel train after a while. Additionally, the bits that do not burn wholly get deposited on the catalyst, something that ends up poisoning platinum-palladium of your car’s cat converter.

Is It Safe To Run Lacquer Thinner In Gas Tank?

If you put lacquer thinner in your fuel tank, it can have the effect of dissolving some gums besides depositing substances in the fuel system. Consequently, it can lead to harmful effects on seals, hoses, and gaskets. Additionally, corrosive compounds in the lacquer thinner can also damage sensitive components, plastic parts, and rubber fittings.

It, however, becomes crucial to note that lacquer thinners come in different types based on the manufacturer. Therefore, the constituents of one brand of lacquer thinner can prove different from another manufacturer’s products, as much as the base constituents are the same. Because of this, it becomes essential to check the constituents of the lacquer thinner you buy.

What’s the best way to clean a catalytic converter?

1. Do nothing

Because catalytic converters clean themselves. It is essential to understand that it is unnecessary to incorporate anything else into your tank when cleaning your cats. The heat at which the catalytic converter operates proves sufficiently high to keep it clean. Therefore, avoid using lacquer thinner to clean the converter.

However, when you burn something else besides gasoline, it becomes possible for the catalytic converter to get clogged. An excellent example entails burning oil, leading to carbon accumulation or the honeycomb disintegrating and clogging the passages. Consequently, you will begin noticing the catalytic converter overheating or glowing red from the high heat.

2. In case you want to clean it, the best way is to actually remove and soak it overnight in ordinary Dawn dishwashing soap

The detergent will unclog and clean the clogged passages of the catalytic converter. However, remember to hose the catalytic converter with clean water the following day before manually inspecting with the aid of a flashlight to see whether the tiny passages are clean and clear.
Sometimes, however, you can do all these but notice that the catalytic converter is still clogged. In such instances, it becomes crucial to use pressurized solvents like spray carburetor cleaners from your favorite parts store (auto).

Buy Dawn Dishwashing liquid soap below:

Dawn Dish Soap

Dawn Ultra Dishwashing Liquid

3. Replacing the clogged and old catalytic converter with a new one

Replacing a clogged and old cat with a new one becomes essential when it proves clogged and old. It will help you save the time and effort of cleaning it repeatedly without tangible results when utilized. Besides, it will also prevent other components and parts from getting affected and having to replace them afresh.

Best Catalytic Converter Cleaner

Cataclean 120007 Fuel and Exhaust System Cleaner

Cataclean 120007 Complete Engine, Fuel and Exhaust System Cleaner

DURA LUBE Catalytic Cleaner

DURA LUBE Severe Catalytic and Exhaust Treatment Emissions Test Catalytic Cleaner

AUTOPROFI OXICAT Catalytic Converter Cleaner

AUTOPROFI OXICAT Oxygen Sensor & Catalytic Converter Cleaner

Final Thoughts

Pouring lacquer thinner down your tailpipe will not help your car run well or get lots of miles out of the fuel you put in it. Please don’t do it. The idea of a quick and straightforward fix can always appeal to even some of the hard workers among us. However, for your car’s catalytic converter, the idea of using lacquer thinner can prove a bad idea, owing to the overarching negative impacts. Having that quick fix of unclogging your cat can lead to replacing diverse parts of your cat and engine. 

Therefore, if you see the OBDI code reading P0420 and your engine light next time, it helps avoid hitting the panic button. Such a reading demonstrates the existence of a problem and not necessarily a bad catalytic converter. It can imply a problem with the O2 sensors or perhaps a problem with your car’s exhaust system. Additionally, it could also indicate an existing crack or hole. Therefore, always try to consider and check such aspects before deciding to replace an expensive catalytic converter. What’s more, cleaning catalytic converter with lacquer thinner is unnecessary as the cat always cleans itself, provided the engine burns gasoline.


1.What should I put in my car’s gas tank when it comes to cleaning my catalytic converter? 

Nothing. It would be best if you always frowned upon any idea of incorporating foreign substances in your vehicle’s gas tank, provided it is not gasoline. It helps prevent damages of parts from corrosions and helps in reducing long-term maintenance costs of your car. 

Can seafoam clean my catalytic converter? Yes, there exists a possibility of seafoam to clean the catalytic converter exists, especially when it comes to cleaning carbon from the engine and the catalytic converter.

2.How do you realize you have a problem?

If your car’s check engine light comes on when the engine is running, and you find out that code P0420 is stored in the computer, you have a catalytic converter issue. Usually, there’s some exhaust leak or a problem with the oxygen sensor. Cleaning the catalytic converter might make your car run better for a while, but ultimately the problem will persist until you get that part fixed or replaced.

ANCEL AD310 Classic Enhanced OBD II Scanner Car Engine Fault Code Reader CAN Diagnostic Scan Tool-Black

ANCEL AD310 OBD II Scanner

Autel AutoLink AL319 OBD2 Scanner Automotive Engine Fault Code Reader CAN Scan Tool

Autel AutoLink OBD2 Scanner

3.Is it possible for a clogged cat (catalytic convertor) to clear itself? 

The answer to this question can prove in the affirmative or not, based on the extent of the clogging. For instance, if the clogging of the catalytic converter proves minor, then there is a chance it can de-clog by itself. However, in most instances, it usually needs a helping hand. For utterly blocked cats, you have no option but to dismantle and unclog the cat manually.

Most recent catalytic converters get stuffed with ceramic structures that resemble a honeycomb, unlike older versions that possessed complex filters. It, therefore, becomes easy for these new cats to get clogged under specific conditions. For instance, when you engage the fifth gear for long and emit plenty of soot. Changing bad habits become integral in this respect.

4.How can you identify a clogged or blocked catalytic converter? 

The most obvious symptom of a clogged catalytic converter entails the absence of power during acceleration. It is a situation that gets worse as the airflow rates increase. While this may not necessarily illuminate your car’s MIL, it often proves deadly. Additionally, converters hardly die but get killed by our reckless actions. For instance, ignition misfire sends raw air and fuel to the catalytic converter.  

Other symptoms may include engine overheating, a sulfur odor, and poor economy

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