Can a Catalytic Converter Unclog Itself?

The catalytic converter (cat) is an emission control device found in cars. The metal component causes the chemicals given off by a car’s engine to break down into less harmful compounds before releasing them into the atmosphere. However, it sometimes clogs up and causes a car not to run correctly, but can a catalytic converter unclog itself?

A catalytic converter can technically unclog itself, but some action is still required on your part. Specifically, you can start the process by driving at 4000-6000 revolutions per minute for at least 30 minutes each month. You can also add a fuel cleaner to the tank.

In this article, I’ll explain how a catalytic converter can, in a way, unclog itself. I’ll also discuss what happens when a catalytic converter goes bad, the signs that suggest it might be clogged, and methods for how to unclog one.

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How a Catalytic Converter Unclogs Itself (With Your Help)

A catalytic converter unclogs itself when it’s heated up. Therefore, the best way to unclog a catalytic converter is to drive your car at high-revs (4000-6000 RPMs) for at least 30 minutes each month, which is usually done by taking a lengthy highway trip.

There are other methods to unclog a catalytic converter, but this one requires no effort besides driving, so it’s a great way to get your catalytic converter unclogged.

However, the only natural way to know if you’ve succeeded is if you notice an improvement in your vehicle’s performance.

How to Unclog a Catalytic Converter Without Removing It

This method requires you to clean out the clogs in your catalytic converter with a special cleaner.

Once you have the cleaner, follow these steps:

Read your car’s manual to determine the correct amount of cleaner needed to unclog the catalytic converter.
Pour the manufacturer-recommended amount of catalytic converter cleaner into your car’s fuel tank.
Drive at high revs for about 30 minutes (remember that 4000-6000 RPMs is the recommended range). This should burn the clog.

Caution: Do not use more cleaner than the manual recommends. Doing so could damage your catalytic converter. Also, monitor your car’s coolant temperature to avoid overheating when driving at high revs.

How to Unclog a Catalytic Converter by Removing It

This method requires you to remove your catalytic converter from the exhaust system, so it’s important to confirm the catalytic converter is clogged or faulty before attempting. Additionally, if you’re not confident in your car-working skills, I recommend getting an expert to help.

Equipment needed:

Jack stand
Socket wrench ratchets
Torque wrench
Oxygen sensor wrench
A bucket or other container (at least twice the size of the catalytic converter)
WD-40
Pressure washer
Engine degreaser

Once you’ve gathered all of your equipment, follow these steps:

Drive your car to level ground. Being on level ground is very important because this prevents the car from falling on you while you’re trying to take it apart. Also, ensure the vehicle is turned off and the parking brake is set.
Jack up your car and ensure the jack is secure and stable before proceeding. Use a hydraulic floor jack to raise the vehicle, such as the Big Red Torin Steel Jack Stands. It can handle a wide range of vehicles, and it’s double locking mechanism ensures it’ll stay in place. Jack stands can also be used to support the car’s exhaust system so it doesn’t fall on you while you’re working.
Carefully remove the oxygen sensors from the rear of the catalytic converter. You’ll need an oxygen sensor wrench, like the ABN Oxygen Sensor Wrench. It’s ergonomic grip and slim design make it easy to access those hard-to-reach spots. Be sure to avoid causing damage or loosening them too much, as they could move out of place and cause problems for the exhaust system.
Remove the catalytic converter. Spray WD40 on the bolts before loosening them with a wrench. If the bolts are welded, call a professional mechanic to get them removed.
Inspect the converter for any signs of damage. You can also shake it to determine if it’s best to unclog or replace it. If shaking produces low rattles, proceed to the next step. However, if the rattles are loud, I recommend replacing the cat instead of proceeding.
Pressure wash and degrease the catalytic converter. Start by pressure washing the converter at low settings with water and degreaser (this will get rid of dirt and grease). Then dilute a degreaser in hot water and soak the converter for a maximum of one hour. Remove from the solution, rinse, then pressure wash using low settings again. Let it drain until completely dry before reinstalling.
Reinstall the catalytic converter and oxygen sensors. Torque the bolts to manufacturer specs (see your car’s manual for details), then test drive your vehicle to determine if the problem has been fixed.

If your catalytic converter doesn’t work after these steps, you may need to replace it.

What to Consider Before Unclogging a Catalytic Converter

Before you go through with unclogging a catalytic converter, there are some things to consider.

Here are four crucial factors to consider to decide whether your catalytic converter requires unclogging or replacement:

Is the catalytic converter broken? When a catalytic converter breaks, it won’t take much for the chemicals to escape into the atmosphere and do damage. This means that if there’s a chance that your catalytic converter has broken, you should replace it as soon as possible before taking any further steps toward unclogging it.
Was your catalytic converter recalled? In some cases, a defective catalytic converter requires replacement by law. This can happen when an automaker recalls specific models due to faulty emissions systems.If your catalytic converter has been recalled, unclogging it might not help at all, and it’s best to have it replaced.
Is the catalytic converter sealed shut? When the seal on a catalytic converter isn’t intact, the catalytic converter may not be performing at full efficiency. In this case, it’s better to get it replaced rather than unclogged.If you suspect your catalytic converter seal has been compromised, take it to an auto shop for inspection.
Have you checked for a fuel leak? A fuel leak can cause the catalytic converter to break down or become clogged. If you suspect a leak, consider getting a professional inspection, as it might be difficult to notice. Check for any stains under your car and take note of whether or not the gasoline smell lingers after turning off the engine.

5 Signs Your Catalytic Converter Has Gone Bad

A catalytic converter goes bad when its metal component is deteriorated by the chemicals given off by your car’s engine. As a result, exhaust fills the air instead of converting it to less harmful components before getting released into the atmosphere. This can harm the environment, which is why you should seek to unclog your catalytic converter to reduce carbon emissions.

Let’s discuss the 5 signs that your catalytic converter has gone bad that you can keep an eye out for.

Loss in Gas Mileage or Power

A clogged catalytic converter hurts your engine’s performance, causing your car to lose gas mileage. In turn, this means you’ll have to refill the tank more often. It may also be difficult to accelerate with a clogged catalytic converter, meaning the car will take longer to speed up.

Once you’ve gotten it unclogged, your car should run much better, and you’ll notice an improvement in gas mileage or power.

Your Car Emits Black Smoke

A black-colored smoke is an indication of chemicals in the smoke. The catalytic converter converts these chemicals into less harmful ones before they get released into the atmosphere. Therefore, when the cat gets clogged, these chemicals escape into the environment — the result: black exhaust from your tailpipe.

The Smell of Rotten Eggs

When a catalytic converter gets too saturated with chemicals, it emits hydrogen sulfide as one of its gases. This gas smells like rotten eggs and can cause health problems after prolonged exposure.

Keep in mind, however, even after the catalytic converter is unclogged, it can still emit hydrogen sulfide if the engine is bad.

Failed Vehicle Emissions Test

An emissions test may be required when registering older cars with the DMV or renewing your license plate tags.

If you get an emission test and fail it, then chances are the catalytic converter is clogged. You’ll need to then get your catalytic converter unclogged before attempting to pass another emissions test.

Dashboard Lights Come On (P0420 Error Code)

Most cars come with dashboard lights that turn on when specific problems happen. The “P” in P0420 stands for “powertrain,” and this code implies something is wrong with the transmission, emissions, or engine.

Thus, if your dashboard lights come on and you see this code, then chances are there’s a problem with your catalytic converter.

Here’s a video about the common signs your cat has gone bad:

Final Thoughts

A catalytic converter is an integral part of your car’s exhaust system. If it gets clogged or faulty, you have to unclog it to restore its functionality before more damage is caused.

And while a catalytic converter can unclog itself, you must still start the process (by either driving at high revs or pouring a cleaner into the fuel tank). In the worst-case scenario, you may have to remove or replace the cat, so it pays to be prepared.