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Do I Need the Genuine Factory Catalytic Converter for my '03 Elantra?

My CEL just turned on yesterday and I took my 2003 Hyundai Elantra to my local mechanic, whom I trust. He said my catalytic converter needs to be replaced. My car has 125k miles. The estimate he gave was about $900 for the converter (genuine, factor Hyundai part) and $100 or so for labor for a grand total of around $1000. He runs a local, independent shop but strongly recommended that I use the genuine Hyundai part. I called another mechanic near my office whom I also trust and he quoted me a price $200-$300 less because he uses an after-market catalytic converter, which he claims will work just as well (is the same quality and matches the specifications, etc.).

I’m not in a position to buy a new car and so my only real option is to keep this one running for a couple more years. Can anyone provide some input about whether or not I should go with Mechanic 1/the genuine Hyundai catalytic converter part/$1000 OR Mechanic 2/$600-$800/an after-market catalytic converter?

My gut tells me I’ll be OK with the after-market so that I can save some cash… can anyone comment?

Thanks for the help.

I was unsuccessful in finding an exhaust system diagram, but I do know that you have two catalytic converters, one built into the exhaust manifold and one built into the exhaust pipe down the line. In many cars of this vintage, only the primary converter is monitored.

Be certain that you know what you’re getting for your money. And get a Haynes manual at the local bookstore to familiarize yourself with the system. That $200 price may be just for the rear converter, and that may not put the light out.

Additionally, you do not need an OEM converter, but you do need an “OEM replacement” converter, also know as a “direct fit” part. Some shops offer a very low price but just weld in a generic converter and you want to avoid this.

In short, be sure of what you’re getting.

Make sure to get a second opinion and even a third. There are a lot of good catalytic converters replaced because mechanics don’t do a little troubleshooting to find the real problem. A CEL light on does not always mean a bad cat or even an 02 sensor. Have your codes read at a large auto parts store then post them here.

I found images of the exhaust system and of the manifold (hsowing the upstream cat converter) for you. I don;;t know if they’ll help you, but here they are.


Unless an emissions test enters into this, there is no “need” to buy ANY catalytic converter…

The CEL was illuminated by the rear oxygen sensor, not the converter…If you MUST start replacing parts because of a dashboard light, I would replace that part first…

125K on a cat seems a little low. Most cats last more miles than that. But let’s assume the mechanic has done all the necessary tests and verified the problem is actually the cat. Before deciding which cat to use for replacement, be aware that some states – like Calif – have stringent requirements on what make/model of aftermarket cats are allowed to be installed as replacement parts. If you live in one of those states, make sure the cat being installed is on their listof approved cats for you car. Otherwise you may fail the state’s emissions test on the nex go-a-round.

All catalytic converters be they direct fit or universal must meet the EPA/CARB standards for all sold on the aftermarket. This includes the subtrate matrix and the wash coat. The substrate matrix is the number of cells per sq/in x length, and the wash coat is the grams of the noble metals applied to the total surface area of the substrate.

The EPA can enter the manufacturing facility at any time and remove any number of samples of the finshed catalytic converters to be taken back to be tested. And if any fail, the EPA can then demand that manufacturing stop. Then the EPA will then investigate the manufacturing process to see if it deviates from the specifications that were submitted to the EPA for cerification to manufacture the catalytic converters. And if it does you lose your certification from the EPA.

I use to make prototype catalytic converters for diesel engines. And when working with the EPA, you better be on your toes.


Tester, the problem with non-direct fit generic cat converters is that shops will often install the new one based only on physical fit and not on ratings. One place that I know of simply welds in whatever fits, and it doesn’t always do the job.

I stand by my recommendation to use only an OEM-replacement part, one designed to replace the original directly. That should not be construed to be confused with an OEM part, one made by the actual manufacturer of the original converter.

Not true. When you order a universal fit converter the parts store still needs to know what vehicle it’s going on. Not only for the proper catalyst, but also for the proper pipe size.


Yes, it is true. If you get the part at the parts store you are correct, but you cannot make the assumption that a muffler shop will install a muffler based upon the correct listed part. I know for a fact that one simply stocks a number of generic converters and grabs one that fits.

But in this car the monitored converter is integrated into the exhaust manifold, makng that approach impossible. My point in making sure of what’s being quoted is to be sure that the monitored converter is the one being replaced. The $200-$300 price quote suggested to me the possibility that the quote was only including the downstream converter, and that won’t help.

@Tester, since you have experience with cat manufactur … I’ve always been curious about why they cost so much. I understand the raw materials are expensive. But don’t they recycle the old cats to make the new ones? So they don’t have to mine the minerals again. Just dump the old ones into the mix and reprocess them into new cats. It wouldn’t seem that would be that expensive to do. i mean I can’t see that it would result in a retail price of $1000 or more for a single cat. What am I not understanding?

They’re expensive because of the nobel metals that are used. The larger the cat the more expensive it is.

They do recycle the nobel metals from old cats to make new ones. If I were to recycle a 14" dia X 16" long Diesel Oxidizing Catalytic converter, I’d get about $300.00 from the recycler for the nobel metals.


Yep it’s an expensive, involved process. The actual catylists differ so it’s an involved process. The catalyst has to be extracted, refined, and applied to a new substrate (the supporting structure).