How to Replace the Key Fob Battery in a Lincoln MKS

1. Remove the backup key from the transmitter.
2. Twist a thin coin in the slot hidden behind the backup key slot to remove the battery cover.
3. Take out the old battery.
4. Insert the new battery, following the orientation shown inside the IA key, and press it down until fully seated.
5. Snap the battery cover back onto the transmitter and install the backup key.

• Battery type: one coin type three-volt lithium CR2032 or equivalent.
• Do not wipe off any grease on the battery terminals or on the back surface of the circuit board.
• Replacing the battery does not de-program the IA key from the vehicle.

Source: 2012 Lincoln MKS owner's manual, PDF page 117. 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.