How to Replace the Key Fob Battery in a Cadillac ATS

1. Press the button on the side of the transmitter near the bottom and pull the key out.
2. Pry the two halves apart with a flat tool in the bottom center of the transmitter, not the key slot.
3. Remove the old battery without using a metal object.
4. Insert the new CR2032 or equivalent battery on the back housing with the positive side facing down.
5. Align the front and back housing and snap the transmitter together.

• Replace the battery when the DIC displays REPLACE BATTERY IN REMOTE KEY.
• Do not touch the transmitter circuitry, because static from your body could damage it.

Source: 2019 Cadillac ATS owner's manual, PDF pages 35, 36. 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.