1. FCC ID
Printed on the back of most fobs or inside the case. It identifies the transmitter. Same FCC ID is the first requirement.
2. Part number
Two fobs with the same FCC ID can still differ in chip or buttons. Match the maker's part number where possible.
3. Frequency
US cars mostly use 315 MHz; some newer ones and many European models use 433 or 434 MHz. Wrong frequency, no remote.
4. Chip
The start chip has to match your car's immobilizer. Sellers often list it; if not, ask.
5. New or used
Many used smart keys are locked to the first car and can't be reused. Some can be unlocked, many can't.
Then send us a photo
Photo of the back of the fob or the listing. We tell you if it will work before anyone drives out. See program a key you bought.
Written by the Keyhub Locksmith team, a mobile car locksmith in Marietta, GA. Updated October 23, 2026.