Hyundai Ioniq 9 key fob battery
Every model year listed for the Hyundai Ioniq 9 has a proven battery. The most common answer is CR2450. Rows below run oldest to newest; a year can appear twice when the car came with more than one kind of key.
- 2025-2026Smart key
CR2450
FCC ID TQ8-FOB-4F61M43Two sites agree: bestkeysupply.com and transponderisland.com (checked Nov 1, 2026)
Find CR2450 on Amazon
Changing the battery
Smart key (push-button start)
- Find the small release on the edge or back of the fob and hold it while you pull out the metal emergency key.
- Use the slot where the metal key sat. Twist, do not lever hard, and work along the seam until the halves separate.
- Pop the old battery out with a toothpick or plastic pick, not a metal blade, and seat the new one with the + side matching the old one.
- Close the case until it clicks all the way round, put the metal key back, then try the buttons and a push-button start.
Hyundai smart keys usually have a button that releases the mechanical key; a flat tool in the gap then opens the case.
A CR2450 is 24.5 mm across and 5.0 mm thick, much fatter than a CR2032. A thinner cell will rattle and lose contact, so buy the exact size.
Coin cells are a choking and burn hazard for children. Store the spares in their original pack, out of reach.