How to Clean a Catalytic Converter without Removing It

If you are a car owner, your job is to keep it undamaged and in the best possible condition. One of the most important factors that keep the car running is the catalytic converter. 

A catalytic converter has one job: it transforms toxic exhausts into fumes that have less harmful toxins for the environment. The catalytic converter is a heavy device because it’s made of mostly heavy metal.

Therefore, the process of removing a catalytic converter won’t be a piece of cake for you. But no worries, in this article, we’re going to show you how to clean a catalytic converter without removing it. 

Does Seafoam Clean Catalytic Converters?

First, there is one question that needs to be answered: does seafoam clean catalytic converters? Seafoam is recommended but only for certain situations.

Seafoam might efficiently clean the carbon from the motor. In case the CAT is still working effectively, it will burn this off.

Some users even complain about seafoam. As for their plugged catalytic converter, sometimes the problem lies in the hardware parts and it causes gumming. Therefore, they might have to replace it.

How to Clean a Catalytic Converter without Removing it

If you have a problem with your catalytic converter and are overlooking cleaning it up, first identify the cause of the exhaust gas problem. After that, decide to clean or replace the catalytic converter. 

Before considering cleaning the catalytic converter, check if it is clogged, damaged internal parts, and poor fuel economy.

Here is a step-by-step guide on how you can clean your catalytic converter without removing it:

Step-by-Step Guide on How to Clean a Catalytic Converter Without Removing It

Step 1: Preparation

In order to do check-ups and tests, and more important, fix your catalytic converter, you need the following tools:

  • A hammer or a stick
  • Gloves
  • A suitable cleaning solution

Step 2: Check 

90% of failed emissions tests were incorrectly diagnosed at the test point. An emission test will download stored OBD-II incident codes that may be related to the test failure. 

The main cause might be clogs in your CAT. But it can also be problems with the oxygen sensors or exhaust system cracks. Once the catalytic converter has an issue, it’s time to fix it and sometimes you’ll have to replace it.

There are some things you need to check first:

1. Check if there are any excess clogs: If the catalytic converter is too clogged, the engine may not be able to start.

2. Check for damages on the inside: Hit the catalytic converter slightly with a stick and listen for abnormal noises. It shows that damages have been done and it’s time to get a new CAT.

3. Check for excessive oil consumption: The culprits might be a damaged piston ring, cylinder cap guide, or fuel injector. Any cleaning methods will not save your CAT.

After checking your catalytic converter and there have been no issues with damages or clogs, you will have to clean it by hand. The best method is to use water and a thinner lacquer. 

However, there are no steps or proven procedures for cleaning catalytic converters, so you may want to look for some additive detergent directly, like oxidate or cataclean, which help to remove the carbon residue slowly before testing.

Step 3: Add a Cleaner to Your Fuel Tank

If there is no problem with the internal oil, you may use a cleaning solution such as the Cataclean. If your tank needs refilling, remember to refill it with premium gas then you can pour the product in.

Types of engines that can go with this product are:

  • Petrol
  • Diesel
  • Hybrid

By doing this, you will clear every area of the oxygen sensors. At the same time, your CAT and exhaust system will be cleaned thoroughly.

Step 4: Rev The Engine at High RPM

Drive your car around town to see how it goes. Normally, this product works almost instantly on any model of cars. But if the error code P0420 on your dashboard has not disappeared, you might need to run a few extra miles to see if it has worked or not.

If your catalytic converter is hot, try driving at high RPMs over 3000 for a long way for about an hour. Because when the RPM is high, the cleaning solution can reach the catalytic converter and dissolve clogs.

Tips and Tricks

  • If there are mechanical issues with the catalytic converter, the Cataclean will not work and might damage your CAT. The Cataclean is only suitable for catalytic converters that might have run with some burnt oil before.
  • If the Cataclean does not work on your catalytic converter, try putting in Lacquer thinner. This is the last resort. In the event that it still does not work, you may have to replace it.
  • The last thing in this tips list is to try unclogging your catalytic converter. If you can’t, then it’s time to call the professionals and let them save the catalytic converter.


If you are having a hard time with the code P0420, we hope this article from ChocolateaAndCraft on how to clean a catalytic converter without removing it has solved your problem. 

Removing the catalytic converter is no easy task. You are going to need a lot of work and effort if you are not a professional. You should try this method and see how it goes!

Stay tuned for our next posts!

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