Blog Car Care Advice How to Unclog a Catalytic Converter (+ Can It Unclog Itself?)
Car Care Advice

How to Unclog a Catalytic Converter (+ Can It Unclog Itself?)

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The catalytic converter is responsible for converting harmful emissions from your engine into less harmful gases. However, over time, it can become clogged due to excessive carbon deposit, unburned fuel, and carbon monoxide.

What can you do about it?

In this article, we’ll give you a step-by-step guide on how to unclog a catalytic converter using two methods. We’ll also explore the symptoms of a clogged catalytic converter, how to prevent catalytic converter failure, and much more. 

This Article Contains:

Let’s get started!

How to Unclog a Catalytic Converter

The catalytic converter (cat converter) in your car’s exhaust system converts polluting gases into less dangerous ones. When clogged, it can hinder the overall performance of your engine. Plus, it will trigger the check engine light and an OBD (On-Board Diagnostics) code. It can also cause you to fail an emissions test, so you’ll want to get it fixed.

Before unclogging your cat converter, ensure it’s not damaged beyond repair. 

Now, if your catalytic converter is just clogged with debris and carbon deposit, you can unclog it in two ways: 

1. Unclogging the Catalytic Converter Without Removing It

For this method, you’ll need a catalytic converter cleaner.

Catalytic converter cleaners are fuel additives you pour into your gas tank. But when picking fuel additives, ensure that it’s compatible with your vehicle.

Here’s what you need to do:

  1. Ensure that your gas tank has about 15 liters of fuel.
  1. Find the correct fuel and catalytic converter cleaner ratio (you’ll likely find this information on the cleaner’s container.)
  1. Pour the catalytic converter cleaner into the gas tank.
  1. Take the car for a drive at a minimum of 2500 RPM for 30 minutes. This way, the fuel mix can efficiently clean the catalytic converter.
  1. Reset the OBD code (if one was triggered) and re-read the catalytic converter to see if the code still pops up.

If you notice improved car acceleration, engine performance, and less black exhaust fumes from the exhaust pipe, you mostly have a clean catalytic converter.

Note: This method works when the catalytic converter isn’t overly clogged. It also helps clean your vehicle’s exhaust system and oxygen sensor. 

2. Unclogging the Catalytic Converter by Removing It

If the first method doesn’t work, use this method to clear a blocked catalytic converter.

This process is labor intensive, so you may need to call a mechanic if you aren’t familiar with catalytic converter repair.

For this method, you’ll need a:


  1. Ensure that you give your exhaust system enough time to cool down to avoid getting burnt.
  1. Raise your car and keep it suspended using jack stands.
  1. Remove the oxygen sensor.
  1. Use penetrating oil to loosen the bolts of your catalytic converter so you can remove them.
  1. Check your catalytic converter by shaking it. If you hear rattling sounds, your catalytic converter is irreparably damaged and needs to be replaced.
  1. If you don’t hear anything, proceed cautiously.
  1. Use the pressure washer to clean the blocked catalytic converter (at low-pressure levels).
  1. Plunge the bad catalytic converter in a degreaser and hot water.
  1. Rinse the clogged converter with the pressure washer and dispose of any catalytic converter deposits that fall out.
  1. Allow the catalytic converter to dry before reinstalling it.
  1. Reinstall the oxygen sensor, and you’re good to go!

We’ve mentioned two unclogging methods. However, in some cases, the catalytic converter may be capable of unclogging itself.

Can a Catalytic Converter Unclog Itself?

Yes, it’s possible for a catalytic converter to unclog itself. But that can only happen when the exhaust system gets hot enough. 

What can you do?
Drive the car at high speeds for a few miles. Try to get to 2500-3000 RPMs. This way, the exhaust system heat will burn off the catalytic converter deposits and unclog the converter.

This method should work in theory, but there’s no guarantee that it’ll successfully resolve the issue. That’s why it’s better to leave unclogging to a professional. 

Now, let’s explore the costs of unclogging a catalytic converter.

How Much Would it Cost to Unclog a Catalytic Converter?

If you simply have a clogged catalytic converter, you can purchase a catalytic converter cleaner for roughly $8-$20.

However, replacing an irreparable cat converter can cost between $450 and $2600, depending on the vehicle manufacturer and labor rate. This component has a precious metal composition of platinum, rhodium, and palladium, which drives its high cost.

That’s why it’s imperative to know the difference between a clogged catalytic converter and a damaged catalytic convert, as repair costs can vary quite largely.

Let’s look at symptoms, next.

What are the Symptoms of a Clogged Catalytic Converter?

A clean catalytic converter works with several components, like the exhaust pipe and exhaust manifold, assisting in the exhaust flow. These parts work together to transform harmful emissions, such as carbon monoxide, into less dangerous exhaust gases, like carbon dioxide.

But a clogged catalytic converter means the catalyst system efficiency is affected, and can impact the engine and fuel pressure. 

Here are a few telltale signs to watch out for:

Now, let’s look at ways to identify the root cause of your issue.

What Causes a Clogged Catalytic Converter?

All catalytic converters may clog up over time. 

However, there are a few additional factors that can hasten the process:

  1. Unburned fuel: Incomplete combustion leads to unburned fuel, which burns the catalytic converter. This results in a partial or complete meltdown and blockages.
  1. Leaking coolant: Engine coolant may leak into the exhaust system if the engine has faults. The coolant combines with carbon deposits in the cat converter and creates soot, which blocks the catalytic converter and restricts exhaust flow. 
  1. Oil slipping into the exhaust system: Engine oil leakage can spill into your exhaust system. There, the oil combusts, releasing thick soot that clogs the catalytic converter.
  1. Damaged spark plug: A damaged spark plug fails to ignite the engine properly, which leads to excessive unburnt fuel in the exhaust system. The unburnt fuel accumulates anytime there’s an engine misfire, leading to clogging.
  1. Structural damage: A damaged catalytic converter may break into little pieces that clog the system. 

Next, let’s explore how urgent it is to fix a clogged catalytic converter. 

What Happens if You Drive with a Clogged Catalytic Converter?

While you can drive with a clogged catalytic converter, doing so may lead to catalytic converter failure. 

Furthermore, a clogged catalytic converter causes the engine to misfire, and the accompanying unburned fuel increases engine heat and back pressure. This can lead to engine failure and increased repair costs.  

So, it’s best to avoid driving when you suspect a clogged or faulty catalytic converter and get it fixed soon. 

Looking for tips to avoid a catalytic converter problem?

How to Prevent Catalytic Converter Failure

The best way to prevent catalytic failure and high catalytic converter repair costs is to follow your vehicle maintenance plan. 

However, here are a few additional tips to prevent catalytic converter failure:

Closing Thoughts

You can use the methods above to unclog a catalytic converter. But if you’d rather avoid the trouble, you can contact a professional for help. 

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