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How To Tell If A Catalytic Converter Is Aftermarket? [Step By Step Guide]

How To Tell If A Catalytic Converter Is Aftermarket? [Step By Step Guide]

When purchasing a used car, you’d want to check out all the components carefully to make sure you’re getting what you are paying for. In this regard, it is particularly important to check the catalytic converter, as it is one of the most expensive car parts.

Of course, you should avoid buying a car that might require a cat converter replacement in the near future, or at least pay a lower price for the car.

When looking at the cat converter, it’s also crucial to check whether the component is original or aftermarket. Usually, original catalytic converters are more valuable and of better quality.

How to tell if a catalytic converter is aftermarket?

OEM (Original equipment manufacturer) catalytic converters come from the same brands that manufacture the cars, which means they are a perfect fit for the respective vehicles.

Moreover, original catalytic converters are of better quality and contain larger amounts of precious metals. In most cases, aftermarket cat converters contain just the bare minimum amount of metals necessary to get the job done. While this makes the component much cheaper, it also means that the cat converter will wear out faster and require a replacement.

When inspecting a used car that you plan to buy, here’s how you can check whether the catalytic converter is original or aftermarket:

1. Look for the manufacturer’s stamp

Most OEM cat converters carry a stamp from the manufacturer. This is one of the most obvious signs of an original component manufactured by the said brand. The stamp generally lies next to the serial number engraved on the cat converter. It might be either the name of the brand, or their logo.

2. Check the weld quality

The craftsmanship of the component’s installation is a great indicator too. Naturally, a catalytic converter installed using sophisticated machinery during the automotive manufacturing process would look better than one installed by a local shop.

An OEM cat converter will have clean welds and smooth seams.

However, while messy welds indicate that the cat converter isn’t the same one installed during manufacture, it doesn’t necessarily mean that the component isn’t genuine. It is also possible that the car’s owner replaced the original component with another OEM cat converter.


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3. Check out the casing

Aftermarket catalytic converters usually have a silver metal casing with an arrow drawn on it. This arrow indicates the correct installation direction.

Now, OEM cats don’t generally carry this feature as the installation takes place in the factory environment by certified professionals or automated machinery. Such additional instruction is necessary only for aftermarket installation.

4. Read the serial number

In case you cannot find the manufacturer’s stamp beside the serial number, just check out the number instead. While every manufacturer has their own series of numbers, aftermarket cat converters usually have serial numbers starting with the letter N. If you find a cat converter without a stamp and a serial number starting with N, it’s certainly aftermarket.

Among these methods, checking for the manufacturer’s stamp is the most sure-shot way to check whether a cat converter is original or aftermarket.

These methods will also come in handy if you are getting your catalytic converter replaced by a local auto shop that isn’t an authorized service center of your car’s manufacturer.

By being attentive and checking for the above-mentioned signs, you can prevent them from tricking you into buying a cheap aftermarket converter for the price of an OEM one.

How much is a aftermarket catalytic converter worth?

Catalytic converters contain three very expensive metals – platinum, palladium, and Rhodium. The quantity of precious metals in an aftermarket catalytic converter is far less than that in an OEM cat converter.

Naturally, this significantly reduces the value of aftermarket catalytic converters. They cost almost 80% less than OEM converters, which should give you an idea of how small the quantity of precious metals is.

An original cat converter may cost anything between USD 500 and USD 2500 on an average. On the other hand, aftermarket cats mostly cost less than USD 200.

In some cases, they might even be as cheap as USD 60. This also reflects in the scrap value of the cat converters. While an OEM cat converter can fetch you quite a decent sum of money, an aftermarket one might barely be worth the hassle.

This is one of the biggest reasons you need to check the catalytic converter before purchasing a used car. Don’t allow the seller to trick you into paying the same amount that you would pay for a car with an OEM cat, if the vehicle actually has an aftermarket cat instead.

Are aftermarket catalytic converters okay?

Now that you have learned how drastically cheaper aftermarket cat converters are compared to their OEM counterparts, you might be wondering if it’s okay to buy them.

Especially if your auto warranty does not cover the cat converter and you need to replace it, you may not have the necessary budget available at the moment. In such a scenario, installing an aftermarket catalytic converter will naturally sound like a very convenient idea.

Well, while aftermarket converters are manifold cheaper than OEM cats, they do have certain drawbacks:

1. Short lifespan

While an OEM catalytic converter usually has the same lifespan as the car itself, this isn’t the case with aftermarket cats. This is because aftermarket catalytic converters are often pre-used products that have already sustained wear and tear.

The quantity of precious metals, i.e., the catalyst is almost negligible, which means they wear out faster. If you do install an aftermarket cat converter, expect to need a replacement at any time.

2. Higher emissions

As aftermarket cat converters aren’t of the same standard as OEM cats, they aren’t as efficient at reducing emissions either.

Especially due to the amount of precious being very little, these cheap cat converters can’t control emissions properly. This can cause your car’s exhaust fumes to become much more toxic compared to when it uses an OEM cat converter.

3. Regulations

Due to the severe environmental impacts of vehicle emissions, there are strict laws regarding the use of catalytic converters. Your car must have a cat converter that meets the regulations and doesn’t exceed permitted emission levels.

Moreover, different vehicles have different types of emissions, and you need to install a cat converter designed to regulate the exact type of emission generated by your car. If the component doesn’t meet these requirements, you could be facing expensive fines.


Differentiating an aftermarket catalytic converter from an OEM catalytic converter is quite easy. Now that you know how to go about it, you won’t fall victim to anyone trying to trick you into buying an aftermarket cat converter.

As for deliberately buying an aftermarket converter yourself, just be careful about it. We highly recommend buying original catalytic converters, as they are far more reliable, efficient, valuable, and meet all regulations.

If you can’t afford to replace a stolen or bad catalytic converter with an OEM component at the moment, you may temporarily use an aftermarket cat converter. However, make sure that it meets all the regulations.