Eight Handy Tips for How to Clean A Catalytic Converter With Ease

Man is going to remove the catalytic converter

The purpose of a catalytic converter is to reduce harmful emissions as exhaust gas exits your vehicle. Burning fuel produces carbon monoxide, nitrogen oxides, and hydrocarbons. Learn some tips on how to clean a catalytic converter below.

These gases go through your exhaust system, and your catalytic converter reduces harmful emissions through oxidation and reduction reactions. You will need to clean or replace this part if it doesn't function properly.

Do You Need To Clean Or Replace Your Catalytic Converter?

Before worrying about how to clean a catalytic converter, you need to make sure that the problem is coming from this part. Some issues with performance and exhaust gases can come from a faulty engine, O2 sensor, or even a leak in your exhaust pipe.

Here are some of the most common symptoms of a clogged or damaged catalytic converter:

  • Failing an emission test
  • Engine stalls
  • The engine doesn't respond to acceleration
  • The vehicle doesn't start
  • Change in fuel economy
  • Fuel vapor coming out of the carburetor
  • Check Engine light comes on
  • Unusual noises coming from the exhaust system
  • Changes in the exhaust, especially with the smell
  • Excessive heat under your vehicle
  • P0420 code appears on your dashboard diagnosis tool
  • Signs of damage or discoloration on the outside of the converter

A clogged or faulty catalytic converter can prevent air from properly circulating through the exhaust system. This problem can spread to the engine where it will increase pressure and impact engine performance.

You should also keep in mind that the P0420 diagnosis code can appear if there is a faulty O2 sensor or another issue in your exhaust system such as a leak.

A faulty O2 sensor can cause some of these symptoms. You should take your vehicle to a repair shop and have professionals perform an emission test with and without the O2 sensor to determine if you need to replace this part.

Cleaning your catalytic converter may or may not fix the problems you are experiencing. If there are signs of damages or discoloration on the part, you will need to replace it. You will also need to figure out what caused the clog or damage so that you can address this issue and avoid damaging the new converter.

Burning A Clog

In some cases, it’s possible to clean a catalytic converter by simply burning the deposits that are clogging this part. You might be able to clear your catalytic converter by getting the part as hot as possible.

Go for a drive on the highway. Try maintaining a speed of at least 55mph for 20 minutes or more if you can. Driving at high speed for a few minutes will cause the catalytic converter to heat up.

If you typically go for short drives or never drive on the highway, it’s possible that your catalytic converter never gets very hot and that carbon deposits build up inside of the part.

If you don’t see an improvement in performance after going for a drive, there are other methods you can try.

Safety First

Safety first signage

Image by succo from Pixabay

If you do some research on how to clean a catalytic converter, you will find guides and videos that recommend inspecting the part and removing it. Some resources recommend using a hammer to gently tap on the piece to see if there are any loose components.

Inspecting the part can help you figure out if there is any damage, and you will need to remove the part if you want to try and clean the inside. However, keep in mind that the chemical reactions happening inside of the catalytic converter can cause the part to reach a temperature of 400 to 600°F.

Catalytic converters get dangerously hot, and a clogged part can generate excessive heat. Don't get under your vehicle to inspect or remove the piece until you are sure the temperature has dropped to a safe level. We recommend waiting several hours after driving, especially if there is a risk of your converter overheating.

Remember always to wear goggles and gloves when working on the exhaust system of your vehicle. It’s also important not to engage in any repairs if you don’t have all the tools needed or don’t feel comfortable with removing car parts.

Know How to Remove Your Catalytic Converter

Some vehicles have a welded catalytic converter. Removing this part is very difficult and requires you to use a rotary saw to cut through the exhaust pipe.

We don’t recommend removing a converter welded to the exhaust pipe. Re-installing the part after you clean it will be challenging since you will have to weld it back in place. It's best to take your vehicle to a repair shop if you have a welded converter since you might need more extensive exhaust repairs.

A majority of vehicles have bolted catalytic converters that you can remove with a few simple tools. You might need to remove the O2 sensor first if it’s in the way. You will need an O2 wrench to remove the sensor without damaging it. These wrenches have an offset design that allows you to reach the sensor easily.

You can usually remove a catalytic converter by loosening some bolts and sliding this part down the exhaust pipe. The fasteners or bolts can be difficult to remove because of rust and gunk.

We recommend that you purchase some spare bolts or fasteners in case you damage them when you remove the catalytic converter. If the bolts are difficult to remove, try loosening them with heat or WD-40. Tapping on them with a wrench to create vibrations might also work.

Keep in mind that some states and local legislation make it illegal to remove a catalytic converter yourself. Contact a licensed mechanic to find out if they can remove this part for you and clean it.

Cleaning Your Catalytic Converter with Degreaser

Once you have removed the catalytic converter, shake it to see if you hear any noises. Catalytic converters either use beads or honeycomb structures coated with precious metals to filter and reduce emissions.

If you have a catalytic converter with a honeycomb structure, parts of this structure can break and impact performance. You should be able to see signs of damages on the outside of the component caused by the shock that broke this structure, or hear broken parts rattling inside of the converter. If you notice signs of damage, you will need to replace the part.

Man is removing the catalytic converter

Photo by Malte Lu from Pexels

If there are no signs of damage, the part is likely clogged. Whether the converter is partially or completely clogged, the best way to clean it is to let it soak in hot water and degreaser.

Degreaser will work by breaking down carbon deposits. The cause of excessive carbon deposits inside of your catalytic converter could be an issue with the air-fuel ratio in the engine. Another sign of this problem would be poor fuel efficiency.

If too much fuel ends up in the engine, it will not burn completely, and the percentage of hydrocarbons in the exhaust gases will increase. This percentage might exceed what the catalytic converter can handle and result in carbon deposits that clog the part. Replacing old spark plugs can fix this problem, but keep in mind that there are other possible causes behind this issue.

Pinpointing the source of this issue is important. Carbon deposits will keep being an issue if you clean your catalytic converter and re-install it without addressing the problem that caused excessive carbon buildup in the converter.

Scrutinize the catalytic converter after letting it soak. Let the part dry for several hours before re-assembling it with the bolts or fasteners.

Using A Catalytic Converter Cleaner

You can purchase a catalytic converter cleaner at any auto supply shop. You will need to pour this product in your fuel tank.

Check the instructions of the cleaner you buy. Most cleaners will require you to pour the bottle in your gas tank when you have four gallons of gas left. However, quantities might vary from one product to another.

The catalytic converter cleaner will mix with fuel and spread through your engine and exhaust system. You will need to drive until the tank is empty to see a difference in performance.

You will get better results if you drive for about thirty minutes at 50 mph or faster. Driving fast will help get the catalytic converter hot and clear any existing clogs.

Using a cleaner is a temporary solution. These products can improve performance and clear clogs, but keep in mind that an issue with your engine or air-fuel mix might be the cause behind excessive carbon deposits inside of your catalytic converter.

If problems keep coming back after using a cleaner, you will probably need to replace your catalytic converter or perform additional repairs to address the issue behind the carbon buildups.

What Not To Do

Stop Signage

Image by ndemello from Pixabay

If you look for advice on how to clean a catalytic converter, you will find questionable information online. Some sources recommend using lacquer thinner to unclog your catalytic converter.

Pouring diluted lacquer thinner in your gas tank is not a wise thing to do. The active ingredient in lacquer thinner is an acetone compound that acts as a solvent. Technically, this ingredient could break down carbon buildups inside of your catalytic converter.

However, pouring diluted lacquer thinner in your tank means that this product will go through your fuel system where it will come in contact with several seals. The material used for these seals is a mix of plastic and rubber. Lacquer thinner can cause some severe damage to all these seals, which would result in expensive repairs.

Other sources recommend that you remove the catalytic converter and clean the inside with a tool. Soaking the part in degreaser is safe since you won’t damage the beads or honeycomb structure.

The beads or structure you will find inside of your catalytic converter use a precious metal coating to reduce emissions. Depending on your vehicle, these precious metals will include palladium, platinum, or rhodium.

The problem with using a tool or a brush to clean the inside of the part is that you can damage the honeycomb structure or scratch this coating. The integrity of the precious metal coating is essential since this coating triggers the reduction and oxidation reactions that reduce emission gases when heat is present.

If you accidentally damage this coating, your catalytic converter might no longer function as it should, and you might fail an emissions test.

Cleaning Might Not Be Enough

Catalytic converters don’t fail often, but you should know that you will typically have to replace this part if there are issues with its performance.

Cleaning your catalytic converter by taking your vehicle for a drive on the highway or using a cleaner can save you money. You should try these methods and see if there are any changes. 

Removing your catalytic converter and letting it soak in degreaser is time-consuming, but this method is worth trying since replacing this part can be expensive.

You should keep an eye out for signs of a bad air-fuel mix or issues with your exhaust system after cleaning your catalytic converter. The carbon deposits that cause the clog will start building up again if you don’t address the cause of the problem.

You should also keep in mind that the methods discussed above will remove carbon buildups that prevent air from flowing through the catalytic converter. However, cleaning the part won’t do any good if there is structural damage or if overheating damaged the coating inside of the part.

Catalytic converters can be expensive, but a new part will last for years. Besides, you won’t be able to pass an emission test if there is an issue with your catalytic converter.

Ask yourself if you need to replace your catalytic converter before you try cleaning it. Don’t hesitate to seek help from a professional if you can’t pinpoint the cause behind a clogged or failing catalytic converter or if you need help with cleaning it.

Featured Image via Flickr

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