Can a Catalytic Converter Unclog Itself? (Clear a Clogged)

Can a Catalytic Converter Unclog Itself

Your catalytic converter is a huge part of your vehicle’s exhaust system.

When working properly, the catalytic converter treats all of the exhaust gases released from the engine to remove any harmful elements before they are released into the atmosphere.

A number of chemical reactions occur within the catalytic converter before being expelled as exhaust.

This is why the EPA mandated that all US vehicles have catalytic converters in 1975, and why this component is still a big part of vehicle designs today.

At the same time, catalytic converters can become clogged over their lifetime. When that happens vehicle performance suffers significantly. If left unchecked long enough they can even compromise operation of your vehicle completely.

So, can a catalytic converter unclog itself? Yes, the catalytic converter can clean itself. All you really have to do is dump high-quality catalytic converter cleaner into your gas tank and run it through your system, allowing the cat to work itself clean all on its own.

Let’s find out right now!

Can a Catalytic Converter Unclog Itself?

Catalytic converters can certainly unclog themselves – though they are going to need a little bit of help from you.

In a lot of situations, you don’t actually have to pull your catalytic converter off, clean it out manually, or replace the whole unit completely.

More on that in just a moment, though.

For right now let’s run through how to diagnose whether or not a catalytic converter is clogged, important things to think about before you attempt unclogging, and then will run through the actual step-by-step process for cleaning these clogs out.

How to Diagnose Catalytic Converter Clogs

The first piece of the puzzle for cleaning your catalytic converter is diagnosing whether or not the system is clogged in the first place.

While not everyone is an auto mechanic this is actually one of the easier things to diagnose without a lot of experience.

There are a handful of “signatures” that a clogged catalytic converter makes really obvious, even to the untrained eye.

Some of the things you want to keep your eyes peeled for include:

  • A vehicle engine that is hard to start, if it starts at all
  • A vehicle that seems to stall out for no real reason whatsoever
  • Significant decreases in overall fuel efficiency
  • Very hard acceleration, even with your foot pressed all the way to the ground
  • Dark gray or even black smoke that comes billowing out of your exhaust at all times
  • A rattling noise that isn’t necessarily coming from your engine but is difficult to pin down

You’ll also want to be on the lookout for check engine lights that pop up on your dashboard.

These indicators don’t necessarily mean that your catalytic converter is clogged 100% of the time, but if you’re noticing any of the other symptoms we highlighted above as well as a check engine light glowing on your dashboard the chances are pretty good you need a closer look.

If you smell rotten eggs every time you fire up your vehicle you’re probably dealing with a clogged or failed catalytic converter, too.

This is a more serious symptom that often necessitates completely replacing the catalytic converter altogether though.

Of course, another way to get a clear-cut answer about whether or not your catalytic converter is clogged up is to simply take it for an omission’s inspection.

If your vehicle fails, the inspection the chances are good that your catalytic converter is gummed up and needs to be cleaned out ASAP.

That’s especially true if you’re noticing any of the other symptoms we touched on a moment ago, too.

Read also: How To Check If Your Catalytic Converter Is Bad (6 Common Problems)

Important Things to Think About Before Attempting to Unclog a Catalytic Converter

Before you attempt unclogging, though, there are a couple of things you need to think about.

Sometimes the situation with your cat converter goes well beyond a clogged. Sometimes the cat itself is compromised and needs to be replaced completely.

Is It Beyond Unclogging?

A surefire sign that your catalytic converter is beyond “self-care” and probably needs to be replaced rather than cleaned out is if the engine will not start at all.

A clogged up catalytic converter that is basically sealed shut is going to prevent your engine from creating the vacuum necessary to fire during the ignition process.

You won’t be able to get any airflow, you won’t be able to ignite the engine, and you aren’t going to be able to start your vehicle if your cat is beyond cleaning out.

If this is the situation that you are dealing with it’s time to replace the whole unit altogether.

Is Your Cat Broken?

If your catalytic converter is actually broken it has to be replaced completely rather than just cleaned out.

There are a couple of different ways to diagnose a broken cat converter, but the easiest way is to simply smack your cat with a hammer. 

You don’t have to bash it in with all your force. A gentle tap or two is usually enough to determine whether or not something’s rattling inside.

If you hear a rattling noise that means that the catalytic converter needs to be swapped out. Nothing should be rattling around, everything should be solid. If it is rattling that means something is busted that shouldn’t be.

No amount of cleaning will fix that!

Read also: How to Remove a Catalytic Converter Without Tripping the Check Engine Light

Are You Dealing with a Fuel Combustion Issue?

Fuel leak issues can sometimes cause gasoline to enter the cylinders, getting burned up inside of the catalytic converter.

Even a deep clean with quality catalytic converter fluid won’t be enough to remedy this issue long-term.

Sure, you might get better performance initially. But after a couple of days everything will get clogged up again and you’ll have to spend more time, more energy, and more effort cleaning a system that is only going to let you down over and over.

If it’s a fuel combustion problem you’ll want to swap out your cat ASAP.

How to Unclog a Catalytic Converter

Now let’s run through the actual process for unclogging a catalytic converter (while letting it handle all of the heavy lifting on its own).

Use Quality Catalytic Converter Cleaner

The first piece of the puzzle is purchasing a high-quality catalytic converter cleaner fluid.

There are lots of options available on the market today, but you need to be sure that you choose an option that is designed for the make and model of your vehicle.

You have to be sure that this is a 1:1 match to your vehicle or you could actually do damage.

Do your research, find an option for your car with good reviews, and snap it up ASAP.

Have a Half a Tank of Gas

Secondly, you have to make sure that you have a half tank of fuel in your vehicle.

If you have too much fuel in your tank the cat converter fluid is going to become diluted and will be a lot less effective. It won’t be able to offer the deep clean you’re looking for.

If you have too little fuel in your tank, the cat converter fluid may be too rich and that could cause a whole host of other issues as well.

A half tank of gas is usually “good to go” with most cat converter cleaning fluids. Read the instructions on the bottle before you mix the two together, though.

If it tells you to use a different amount of gas try to hit that level for sure.

Dump Cleaner Into the Gas Tank

The next piece of the puzzle is to simply empty the entire bottle of catalytic converter cleaner directly into the gas tank.

This isn’t going to take very long at all and you don’t have to wait for the mixture to combine with the gasoline itself. The whole process (start to finish) might take 30 seconds or so.

Drive Around for a Half an Hour

After adding the fluid to your gas tank it’s time to jump in and drive your vehicle around for 20 or 30 minutes or so.

It’s important to try and get the RPMs up to at least 3000 and maintain them at that position for extended amounts of time.

You want to be sure that the cat cleaner fluid is flushed throughout the system, dissolving and breaking down any of the deposits that are clogging it up.

You want to be sure that you keep a close eye on your temperature gauge, though.

If you start to see the engine temperatures climb you have to shut things down or (at the very least) slow things down quite a bit.

You don’t want to do irreparable damage to your vehicle with overheating while trying to get your catalytic converter free and clear.

Check Your Cat

The only thing left to do now is to let your vehicle sit for an hour or so before you fire it up again and go for another 30-minute drive.

After that, you can check your cat, check your exhaust, and see if you have any check engine lights left on your dashboard.

If the catalytic converter can clean itself it will be unclogged by the time you run through this process!

If not, you’re going to need to take it to a mechanic for a little more professional hands-on help.

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Jeff is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Reatta. Jeff has been creating written and video content about transportation, automotive, electric cars, future vehicles as well as new, used for more than 18 years. Jeff is based in Boulder, Colorado.

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