How to Replace the Key Fob Battery in a Hyundai Tucson

1. Insert a slim tool into the slot (1) and gently pry open the rear cover of the smart key.
2. Take out the old battery.
3. Insert a new CR2450 battery, making sure it sits in the correct position.
4. Reinstall the rear cover of the smart key.

• Battery type: CR2450
• An improperly positioned battery may discharge and cause smart key failure.
• Keep batteries away from children; a swallowed lithium button battery can cause severe or fatal injury within 2 hours.

Source: 2026 Hyundai Tucson owner's manual, PDF page 121. Steps are summarized in our own words (AI-assisted, checked against the cited pages 2026-10-18). Other model years can differ; your manual has the final word.