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What's New?

Here at CARBCATS we are constantly looking to improve our site and will present any updates or changes here. We love hearing from our users so please email us any comments, suggestions, issues you might have at Thanks!
AUG 2018 Updates
• Part Names: You may have noticed that we’ve converted a lot of the manufacturer names and part number to the part name and number that you would find on the box or at a retailer. This will help users know what part to ask for and expect.
• New Database program: While a user will not be able to see what happens on the backend of a database and website, we recently overhauled ours to run more efficiently, accurately, and frequently. Being accurate and up-to-date are our highest priorities. If you find any discrepancies with the aftermarket database please let us know and we will quickly make sure any errors are corrected. Email us your screenshots for a possible reward!

Tell me more about the site’s database.

CARBCATS maintains a complete and independent database of all Executive Orders issued for every California Air Resource Board (CARB aka ARB) compliant converter. By using this site, the user agrees that on rare occasion there is a chance certain parts are not updated as quickly as it is on the original CARB site. Our goal is to have 100% accuracy with the CARB site and we constantly audit our database to ensure the highest standards.
*CARBCATS is only responsible to make sure our database is as accurate as the CARB database. We are not responsible for inaccuracies in the CARB database. The original database can be found here:

Why use this site versus others?

CARBCATS strives to demystify the CARB converter for consumers by offering the fastest, easiest, and most useful search platform. You will love our user friendly search options and features that present only the results you are looking for. Looking for a previous search? We have a quick option for you to see your last 12 searches. We remove information you don’t need like other Test Group Names/EFNs and Rescinded or Withdrawn parts (which are moved to the bottom of the search results) and allow you to search for either universal or direct fit or both quickly and accurately.

How do I use this site?

The most important piece of information a user needs to have is their Test Group Name, also known as the Engine Family Number (EFN), which is on the emissions sticker on the vehicle. This number is typically located on the underside of the hood or fender wall, depending on the manufacturer, make and model. After entering the correct year, make, model, and engine size of the vehicle, the Test Group Name/EFN must match. The site will return results of parts that are approved to be used on that specific vehicle.

What if the Test Group Name/EFN does not match?

If there is no match with the Test Group Name/EFN, the user must contact their automaker’s dealership for a replacement converter or contact their State’s automotive repair bureau ( for CA). It is illegal to replace a converter with an aftermarket converter that does not have the correct application listed. The vehicle will fail and not pass a visual inspection at their smog station.

What is an Executive Order (EO)?

Executive Order (EO) is the document issued by ARB to exempt a catalytic converter design from the prohibitions of California Vehicle Code sections 27156 and 38391 when ARB’s Executive Officer has determined that the catalytic converter complies with the criteria specified in these evaluation procedures. An EO is required for new aftermarket catalytic converters to be legally advertised, offered for sale, sold, or installed on emission-controlled vehicles. Each EO contains a unique number to allow for proper identification and verification of applicability.

Why are there so many Executive Orders?

Executive Orders can be as small as for 5 vehicles and up to 20,000 vehicles. Each Executive Order is unique in its coverage in terms of vehicles and emissions levels. Manufacturers will determine which vehicles they want to cover and what emissions level will be included. Larger EOs do not necessarily mean better ones. A larger EO may have more coverage and more precious metal loadings, but it may also mean that the converter is overloaded for that application and more expensive for the consumer.

Why are there so many part numbers?

No two parts are alike because of their EO and converter application. Manufacturers will have overlapping coverage for some parts, but a consumer cannot assume any two parts will have the same application. The consumer must use the right converter that matches the year, make, model, engine size, and EFN (test group name). This site will tell you which part is approved specifically for your vehicle.

Why are there multiple EFNs/Test Group Names for my vehicle?

You may have a vehicle that has multiple EFNs. This likely means the car manufacturer made several different emissions level for that particular vehicle. Even though all the vehicles look and drive the same, the car’s emissions control systems are different and need to have the right converter for it. A consumer must verify the EFN/Test Group Name to ensure the right converter is used. It is illegal to install a converter for the wrong engine family number even if the year, make, model, and engine size are the same.

Why do aftermarket parts look different from the OEM?

Aftermarket manufacturers will determine the ultimate look of the converter. Sometimes manufacturers will make it as closely as the OEM, and other times it is not possible to do so. Just because the aftermarket does not look the same does not mean it will not work. Some converters will contain more advanced technology that will allow manufacturers to create smaller and more efficient converters. A consumer should not be surprised to see a much smaller aftermarket part.

What is the difference between universal and direct fit converters?

A universal converter is a converter that may be installed by a professional installer by cutting and welding the converter onto the vehicle. A direct fit converter is guaranteed to fit and replace the original converter from flange to flange or manifold.
While there are universal converters that are approved for some vehicles, it may be impossible to use the converter due to its location and/or physical limitations. A professional installer must assess whether a universal converter can be used or if it must be a direct fit replacement. Universal converters are not guaranteed to fit or be used on every application.

Why don’t all vehicles have an aftermarket part that is compliant?

CARB converters must pass a strict testing procedure to ensure the converter will meet California’s emission standards and meet its warranty requirement of 5 years or 50,000 miles. CARB converter manufacturers are constantly adding new Executive Orders to cover new and old vehicles; however, manufacturers will NOT be able to cover every single vehicle in operation today.

Why are some parts unavailable if they are listed on the website?

CARB will issue an Executive Order for a manufacturer to build converters for those specific applications after the converter passes its strict tests, but a manufacturer will not always have those parts readily for sale. After receiving an Executive Order, a manufacturer at that time will begin to start the manufacturing process.

Do I need to replace my converter?

If your vehicle has a PO420/PO430 code you may need to replace your catalytic converter. However, proper diagnosis is important to determine the cause of the failure and save the consumer money. A converter is not usually the main cause of a PO420/PO430 code unless the converter has suffered from physical damage such as a broken substrate or cracks in the welding. Most converter failures are due to:
Contamination from excessive oil consumption, internal coolant leak, or excessive carbon build up.
Melted substrate from engine misfires that causes the substrate to overheat.
Thermal shock or cold-quenching that occurs when a hot converter is suddenly exposed to cold elements, such as driving through deep water or snow.
If the converter is purple or if there is signs of carbon build up in the converter, the consumer must ensure proper vehicle maintenance is done before replacing the converter. The converter acts like a canary in a coal mine, but you wouldn’t replace a dead canary with a new one expecting the mine to be ok. A converter will tell you if something is wrong with your vehicle, but if you a replace a converter without addressing any other issue; you will likely have another failure in the near future. Plus, not doing any proper repair work for the check engine light code may void the warranty of the new converter. Save yourself a lot of money by getting a proper diagnosis of your vehicle and fixing the issue that is causing your converter to fail and not just replace the converter!

For more information about this website and other FAQs, please email