FCC ID vs Part Number vs Serial Number on a Key Fob: Which One Matters?
By · Last updated: October 28, 2026
The numbers you will see on a key fob
Open the back of your key fob, or look under the battery cover, and you will usually find a small block of printed text. Not every fob prints everything, and some numbers are easy to confuse.
- FCC ID: a code issued when the transmitter was certified with the U.S. Federal Communications Commission. It identifies the radio inside the fob. Example formats from our listings include N5F-A08TDA and M3N-A2C31243300.
- Part number (PN) or OEM number: the automaker’s reference for the fob, for example 164-R8134 or 95430-4Z100. Different suppliers and model years may use different part numbers for similar fobs.
- Serial number: an identifier for that individual unit. It is not used to look up a replacement.
- Frequency: often printed in MHz. It is tied to the FCC ID and must match the vehicle.
Is the FCC ID the same as the serial number?
No. The FCC ID tells you which transmitter design the fob uses, so many fobs share the same FCC ID. A serial number is unique to one unit. When you search for a replacement, use the FCC ID, not the serial number.
Which number should you match?
- FCC ID first. If the replacement lists the same FCC ID as your fob, the radio matches.
- Then the part number. A matching part number gives extra confidence, but a different one does not automatically mean the fob is wrong, since suppliers use their own numbering.
- Then the physical details. Count the buttons, check whether there is an emergency blade or a flip key, and compare the shape.
Use the UrbanX FCC ID lookup to search by FCC ID, or start from your vehicle with the VIN lookup. If you are not sure which approach to use, our guide on getting a key fob by VIN explains the difference.
How to find the FCC ID when it is hard to read
- Carefully open the fob case along its seam with a plastic pry tool or a coin. See our guide to key fob batteries for how fobs open.
- Check inside the case and on the circuit board side. On some fobs the code is molded into the plastic.
- Use good light and a magnifier or your phone camera. Small print wears off over time.
- If it has worn away, use the VIN lookup or contact us with your vehicle details.
What to do next
After you confirm the FCC ID, check whether the fob needs to be programmed to your vehicle and whether you need a new key blade cut. Our article on key fob replacement cost explains the typical parts of the price.