Catalytic Converter Serial Number Lookup: What It Tells You

Short answer: A catalytic converter serial number lookup matches the code stamped on the converter to a price built from metal test results. It gives you an estimate, not an offer, and a buyer's offer may be lower. The code is usually shared by many converters, so it does not identify yours and it does not prove you own it. Many states require proof of ownership before anyone can buy a used converter.

Last checked: November 1, 2026. Sources are Ecotrade, Rockaway Recycling and its RRCats site, each tool's own site or App Store listing, and leginfo.legislature.ca.gov for California law.

Where is the number on a catalytic converter?

Ecotrade, a converter buyer, says each converter has a reference carved or printed on it. RRCats, Rockaway Recycling's converter-buying site, says some do not.

Converter	Where to look	What you may see
GM and Chevy	A corner, the main shield or along the casing	RRCats says these often begin with 126, 127, 253 or 255
Honda	The shield, but do not count on a number	RRCats says most are unmarked and asks for photos of the shield
Other factory units	Corners, under shields and on down pipes	A stamped or etched code
Aftermarket	The outside of the shell	Rockaway says often a silver plate with an arrow

An aftermarket number will not get you much. Rockaway posted aftermarket converters at $5 each on November 1, 2026.

A short video from the Rockaway Recycling channel. The title says it shows how to find the serial number on a converter. Rockaway buys converters, so this is a buyer's advice. Published September 2019.

Is it really a serial number?

Not in the sense most people mean. A true serial number belongs to one item. What buyers call the serial number on a converter is usually a manufacturer's part or reference code, and many converters share it. That is why a lookup can work: someone tested a converter with that code, and the result gets applied to the others.

Why do buyers price by that number?

The value is in the platinum, palladium and rhodium inside, and two converters that look alike can hold very different amounts. The code is a shortcut to that metal loading. Converter Database describes its listings as based on XRF values, meaning X-ray tests of metal content. Without a code, a buyer prices by category, and categories are wide. Rockaway Recycling posted these ranges on November 1, 2026, and says prices can change at any time:

Rockaway's category	Posted range, each
Small GM	$18 to $764
High grade domestic	$68 to $612
Large Chrysler	$92 to $279

These are one buyer's category ranges, not prices for any serial number. A single category running from $18 to $764 is why the number matters.

How do lookup sites and buyer apps work?

You enter the code, or part of it, and the tool returns a price tied to metal markets. We read these listings on November 1, 2026.

Type of tool	Example	Cost or account
Reference database	Converter Database	Has log in and sign up links. The home page does not say what each unlocks
Subscription app	Catalytic Converter Guide	Free to download. Plans listed at $19.99 a month or $149.99 a year
App with buyer prices	Cat DB	Free plan with 3 code searches a day. Account needed after 30 days. Paid plans from $11.99 a month
Buyer's own price book	Ecotrade	You search its buying price once you have an account

PMR, a company in converter processing and refining, warns that serial number databases can rest on a single analyzed sample, that two converters with the same number can differ a lot, and that a number "cannot guarantee a price." PMR promotes assaying whole lots, so it has a stake here. Prices also move with the metals, so last month's screenshot is not worth much.

What if the number is worn off?

Clean the shell first. RRCats suggests steel wool on GM units, and Rockaway has a video on using chalk to make a stamp easier to read. If it really is gone, you can still sell it. RRCats takes photos of the full unit and lists the number as optional on its email form, and Cat DB lets you search by size, shape and brand. Expect a category price.

How does a yard's offer relate to a lookup price?

Treat a lookup price as a reference point and do not expect to be paid it. No tool binds a buyer, a yard has its own costs to cover, and tools calculate differently: Catalytic Converter Guide says it sets values at 85% of market value. A general yard may not look up your number at all. See selling a catalytic converter to a junkyard for how yards and specialist buyers differ.

Have your code and photos ready, and ask two buyers on the same day so the metal prices match. To judge the market, read scrap value and 2026 metal prices, and see catalytic converter value and which vehicles have the most valuable converters.

Do the numbers prove you own the converter?

No. A factory code says what kind of converter it is and nothing about who owns it. Many states require proof of ownership and limit who can buy, so check our catalytic converter laws by state before you sell.

In California, Vehicle Code 10852.5 lets a buyer purchase from an individual only with documentation of lawful ownership, such as a title or registration whose VIN matches the VIN permanently marked on the converter. That VIN mark is a separate thing from the factory code. Under Business and Professions Code 21610, a core recycler generally must pay by a traceable method, not cash, and collect the seller's ID and a photo. In Ohio, our House Bill 210 summary covers the rules in force since October 6, 2026, including a ban on licensed salvage dealers buying converters.

RRCats requires a registration, title or bill of sale just to quote, plus ID verification to complete a sale. This is a summary and not legal advice. If someone offers you a loose converter with no paperwork, walk away.

Common questions

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