How to Replace the Key Fob Battery in a Ford C-Max Hybrid / C-Max Energi

1. Remove the backup key from the transmitter.
2. Twist a thin coin under the tab hidden behind the backup key head to remove the battery cover.
3. Remove the old battery.
4. Insert the new battery with the + facing downward and press it down until fully seated.
5. Snap the battery cover back onto the transmitter and install the backup key.

• The remote uses one coin-type three-volt lithium battery.
• Do not use the backup key to remove the cover or you could damage the intelligent access key.
• Replacing the battery does not erase the programmed key from your vehicle.

Source: 2018 Ford C-Max Hybrid / C-Max Energi owner's manual, PDF pages 52, 51. 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.