These instructions apply to the Hyundai Bayon Mk1 (BC3) 2021-Present. For other models, please choose your vehicle here.
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A weak key is the usual reason a Hyundai Bayon (2021–present) stops locking from a distance or asks you to hold the fob to the start button. The Bayon key takes a single CR2032.
Battery You Need
A single CR2032 3 V coin cell — the standard Hyundai key battery.
How to Replace the Key Battery
- Pull out the mechanical key blade (on keyless fobs) or open the remote.
- Use the slot (or a small coin/screwdriver) to split the fob and reach the cell.
- Lift out the old CR2032, noting the orientation.
- Fit the new cell with the positive (+) side facing up.
- Clip the fob back together and refit the blade.
Lock and unlock from a few metres to confirm.
If It Still Won’t Work
- Start the car anyway — on keyless cars, hold the fob against the start button as you press; the car reads the transponder directly.
- Lock manually with the emergency blade in the driver’s door.
Frequently Asked Questions
What battery does the Hyundai Bayon key take?
A single CR2032 3 V coin cell, positive side up.
Do I need to reprogram the key after changing the battery?
No — it pairs again as soon as power is restored.
How do I open the Bayon key?
Pull out the mechanical blade (keyless fob), then split the fob using the slot or a small screwdriver.
My key still won’t start the car — what now?
Hold the fob against the start button as you press it.
For a no-start with a warning light, check the code on autodtcs.com. See also our Bayon battery guide if the car is dead.
Disclaimer: The information on this page is provided for general guidance only. Always follow your official service manual and safety precautions when working on your vehicle. We are not responsible for errors, omissions, or any damage resulting from the use of this information.
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