How to Clean Your Catalytic Converter

If you’ve recently attempted to have your emissions checked and was told the vehicle failed, it’s quite possible the root source is a clogged or dirty catalytic converter. The catalytic converter is an emissions-regulated component installed within the vehicle’s exhaust system. It removes particulate matter and other harmful emissions prior to exiting the tailpipe. Eventually, this part will become clogged with excessive carbon buildup and will require cleaning or replacement. However, cleaning your catalytic converter is not as easy as you might think. In fact, it’s not even recommended by professional mechanics or a vehicle manufacturer and if done, may even void vehicle warranties.

If you’re having problems with a catalytic converter and are considering cleaning it, first determine the cause of the emissions issue. Then, decide whether to clean or replace the catalytic converter.

Determine the Root Source of Your Failed Emissions Test

90 percent of the time a failed emissions test is incorrectly diagnosed at the point of inspection. An emissions test will download the stored OBD-II trouble codes that might be related to the failed test. Most of the time, the code found is P-0420 — a generic code indicating that the Catalyst System Efficiency is “Below the Threshold.” While most of the time this can be contributed to a clogged catalytic converter, it can also indicate a failure of one of the multiple oxygen sensors, an exhaust system crack, or about a half-dozen different problems. If the catalytic converter is the problem, the majority of the time it is past the point of cleaning and will require replacement.

If you’re trying to diagnose the source of this code, you should start by inspecting the catalytic converter first. Here are three items to verify before attempting to clean the catalytic converter.

  1. Determine if it’s too clogged: If the catalytic converter is too clogged with excessive carbon deposits, the engine may not run. To inspect the inner catalytic converter, it needs to be removed first.
  2. Check for damaged internal parts: If the catalytic converter is the source of your issue, inner parts will be loose or damaged in most cases. One quick way of checking it is lightly tapping the catalytic converter with a hammer and listening for any rattling sounds. These noises indicate damage and require replacement.
  3. Check for excessive oil consumption: Another leading source of a damaged catalyst is excessive oil consumption. This is usually caused by damaged piston rings, cylinder head valve guides, or fuel injectors. If you notice smoke coming from your exhaust pipe, this is likely the issue. Cleaning the catalytic converter will not resolve the problem.

Consider Removal and Manual Cleaning, or Replacement

Once you’ve determined that the catalytic converter is not damaged or too clogged for cleaning, the next step would be to remove it and attempt to clean it manually. The best method is using water and lacquer thinner. However, there is no proven step or process for cleaning the catalytic converter this way, so you might want to search online for a few additive cleaners, such as Oxicat or Cataclean, that help remove carbon deposits slowly before attempting.

As we indicated at the beginning of this article, cleaning a catalytic converter is not recommended by any vehicle manufacturer. It can damage the internal catalyst and render this mandated system useless. The best solution is to have a professional mechanic replace the catalytic converter.

Next Step

Schedule Catalytic Converter Replacement

The most popular service booked by readers of this article is Catalytic Converter Replacement. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Catalytic Converter Replacement reviews

Excellent Rating


Rating Summary


21 years of experience
1307 reviews
21 years of experience
Chrysler Town & Country V6-3.8L - Catalytic Converter - Dacono, Colorado
You did a great job for me!!!! If I ever need some other work on my car I’ll be sure to call you!! Thanks again job well done!!
Subaru Outback - Catalytic Converter - Louisville, Colorado
Robert was on time, got the work done quickly, and gave us great recommendations. Will definitely use him again!


25 years of experience
382 reviews
25 years of experience
Honda Odyssey V6-3.5L - Catalytic Converter - Beltsville, Maryland
Jermaine was great. He fixed my car in a timely manner. In addition, I was over-quoted on the work needed. Jermaine instead fixed my problem and did not upsell me on the work, saving me more than $500 than estimated!
Jeep Grand Cherokee - Catalytic Converter Replacement - Bethesda, Maryland
Incredible customer service-truly puts the customer first and goes above and beyond! So thankful to have had Jermaine work on our car and hope if we need work done in the future we have the opportunity to work with him again!


20 years of experience
587 reviews
20 years of experience
Chevrolet Suburban 1500 V8-5.3L - Catalytic Converter Replacement - Suwanee, Georgia
Arrived early! Assisted with jumping the vehicle. Informative and helpful! Made my first experience with YourMechanic a successful one!
Dodge Caliber - Catalytic Converter - Fairburn, Georgia
Mazyar is highly skilled, very punctual, and professional. He worked on my car twice and I have been very satisfied.


37 years of experience
98 reviews
37 years of experience
Chevrolet Traverse V6-3.6L - Catalytic Converter - San Antonio, Texas
A+++ service and labor was quick. Michael was also knowledgeable and assuring when it came to fixing my vehicle. Would recommend to anyone!
Hyundai Accent - Catalytic Converter Replacement - San Antonio, Texas
He was totally amazing. He explained everything so I understood it all and even gave me some fair suggestions on things I didnt even noticed I needed to get done! I would 150% ask for his help again! Great, Great service and he was fast too!

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


Related articles

What Does the Catalytic Converter Warning Light Mean?
The catalytic converter warning light means the catalytic converter in your engine may not be working properly, possibly due to overheating.
How to Prevent Catalytic Converter Theft
Catalytic converters are easily accessible to thieves looking to make a profit from the precious metals inside.
3 Reasons Your Car Smells like Rotten Eggs
A sulfuric or rotten eggs smell indicates an excess of byproducts left over from failed combustion. Removing the smell requires part replacement.

Related questions

Loud, hot-rod type sound when driving
Hello. It sounds like the catalytic converter gaskets may be causing a leak in the exhaust system. It is also possible that there is a leak or bad baffle in the muffler ( This may be causing the hot-rod sound....
Spark knock
If you are getting spark knock then you may have a bad mass airflow sensor ( telling the computer you are at or above 10,000 feet above sea level and would run the engine lean. Have the sensor tested. As...
replacement of catalytic converter
I wouldn't assume that the rear converter is bad unless the mechanic actually performed a diagnostic on the converter AND then explained to you what was done, what was found and WHY the solution is to replace the converter. If...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 ·