Whether you’re a new locksmith or just a car owner trying to figure out what key to buy, you’ve probably seen weird codes like "FCC ID: M3N-40821302" or part numbers like "13508398" and thought, "What even is this?" Don’t worry—this guide breaks it all down.

What Is an FCC ID?

Think of the FCC ID as a key's radio license plate. It's issued by the Federal Communications Commission to make sure that the remote you're using doesn’t interfere with other wireless devices.

• Why It Matters: If the FCC ID doesn’t match, your remote might not work properly. Even if the key looks the same, it could be running on a different frequency or protocol.

• Where to Find It: Flip over the remote and look at the back or under the battery. It'll usually start with 2-3 letters followed by numbers (like M3N-40821302 or OUCG8D-380H-A).

What Is a Part Number?

The Part Number (PN) is the manufacturer's internal code for that specific key or remote. It tells you exactly what make, model, and year the key is built for.

• Why It Matters: Different vehicles can look identical on the outside but require completely different keys under the hood. Matching the part number makes sure everything from remote start to trunk release works correctly.

• Where to Find It: It's usually printed next to or near the FCC ID. On some keys, it's etched into the shell or hidden inside.

• Two different keys can share the same FCC, but what exactly identifies each one is the PN.

What About the VIN?

The Vehicle Identification Number (VIN) is your car's DNA. It's a 17-character code that tells you the car's make, model, year, engine type, country of origin, and more.

Why It Matters: With the VIN, a locksmith or dealer can look up your car’s exact key specs. It's especially useful when you're not sure which key you need, or if your car takes multiple versions.

Where to Find It:

• On the dashboard (driver side, near the windshield)

• Inside the driver door jamb

• Insurance papers or registration

Why Matching Matters

Here’s the deal: you can’t just order any remote that "looks right." If you want to avoid the headache of failed programming, missing functions, or having to return your key, always match:

• The FCC ID

• The Part Number

• The Frequency (e.g., 315 MHz vs. 433 MHz)

• The VIN (for confirmation)

Even if a key fits in your ignition, it won’t always work electronically if these don’t match. If you mess up the frequency or the PN, it will not program.

How to Make Sure You’re Ordering the Right Key

If you’re a customer:

• Check your original key for the FCC ID and part number.

• Give your VIN to the seller (or locksmith) and ask them to verify compatibility.

If you’re a locksmith:

• Always verify the FCC and PN before programming.

• Use diagnostic tools or dealer lookups with the VIN when in doubt.

Aftermarket keys are a great way to save money, but only if you buy the right aftermarket key. At KeylessCity, we always list FCC IDs, part numbers, and frequency info for every product. Still not sure what you need? Just call us, and we will walk you through it.