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Aftermarket Catalyst Terminology
Posted to Technical Theory Forum on 1/20/2009 14 Replies

Given the recent law changes in California and the posts, I thought it might clear up some of the confusion (or at least not add more to it) to explain some of the terms commonly used with aftermarket cats so it makes a bit more sense. There are some that are quasi-legal terms that are used by the cat regulations and then there are many that are marketing/advertising terms used by the cat manufacturers.

'CARB-approved' -- Should mean that the manufacturer has applied for and received and Executive Order (EO) number from CARB certifying that the specific catalyst model has meant the minimum criteria and been approved by CARB. The proof is an EO #. If it has an EO #, it has been approved. If not, it has not.

EO number -- Executive Order number. Just like other aftermarket emission controls that are not identical to the OEM part (replacement parts) such as intake kits, headers, add-on superchargers, etc, if the part has gone through the legal process to be approved for use in Calif, it gets an EO #. There is actually a document on-line for each EO # that describes the part, the testing that was done to confirm it was legal, and in the case of aftermarket catalysts, all the vehicle applications that the specific part is legal for.

'EPA-approved'/'Federal-approved' -- A marketing term, not a legal term. It means nothing because EPA does not have an approval process whereby they review and approve catalysts. To be legal for sale Federally, there are rules but it is up to the catalyst manufacturer itself to decide their cats meet the rules and thus, are legal. There is no application submitted to EPA nor does anybody review it or issue an approval or anything like that.

'49-state legal'/ 'OBD II-legal'/'OBD-legal'/'OBD-compatible' -- More marketing terms. Again, outside of California, it is up to the catalyst manufacturer itself to decide if its own cats meet the Federal rules or not. The Federal requirements are quite simple--the catalyst must last for 25,000 miles and have at least 70% conversion efficiency for HC and CO and 30% (yes that's not a typo) for NOx. Lastly, the catalyst manufacturer must agree to warranty the catalyst for 25,000 miles including if the OBD system detects a bad catalyst in those 25,000 miles. These terms just mean the catalyst manufacter has decided on its own that its cats meet those requirements. It does not mean the catalyst will have high enough conversion efficiency to pass your state's IM tailpipe test (if you have one) or that it will keep the MIL off for a little while or a long while or that it really 'works' with the OBD system.

'50-state legal' --Another marketing term. CARB approves cats for use in Calif, the manufacturers self-decide for cats in other states. Clearly, if the cat does not have a CARB EO #, it cannot be 50-state legal since it won't be legal in Calif. A CARB EO # doesn't directly make a cat legal in other states but since it is solely up to the manufacturer to decide what is legal in the other states, they typically would decide that any cat that got a CARB EO # has to be good enough for other states. (And yes, that is a very reasonable assumption).

"Direct-Fit" -- A marketing term. Nothing in any regulation talks about direct fit or not. Typically, catalyst manufacturers use this to mean it is a bolt-up type part, not a cut and weld-in type part. It relates only to how the part is installed and doesn't mean a thing about its performance. It does not mean it is 'like the OEM' for catalyst performance or that it has been certified or verified by anybody.

"Universal" -- Another marketing term. The counterpart to 'direct-fit', universal typically means it is a cut and weld-in type part and only refers to the method of installation. Again, it does not mean anything about its performance (or lack of) nor about its legal uses (e.g., it doesn't mean it is legal to put on lots of different vehicles or anything like that).

I won't summarize the new rules again--there have been other posts on that. This link on our website does indeed have some other info if you are interested in the California changes:

It has the label decoding that Chris already linked, some FAQs that we try to keep expanding, some installer tips, etc. for California-installers and shops.

The bottom line--when Randy or others ask about a Calif cat, they mean one with an EO and no matter what the sales guy on the phone tells you, if it ain't got an EO, it is not a CARB-approved cat that has gone through an approval process. If you hear direct-fit, think bolt-in installation but don't assume anything about how well the cat performs. If you hear universal, think weld-in but again don't assume anything about how well it performs or what cars it is legal on.

And, while the coverage is still not great, for those vehicles that do indeed have a CARB-approved cat legal for it, our testing has shown pretty good durability and conversion efficiency that makes me comfortable recommending them to consumers or installers as a reasonable alternative to OEM.

Mike from California

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