How to Replace the Key Fob Battery in a Chevrolet Sonic

1. Press the button on the side of the transmitter near the bottom and remove the key.
2. Separate the two halves of the transmitter using the key or a flat tool near the key slot.
3. Lift out the old battery with a flat object.
4. Insert a new CR2032 or equivalent battery with the positive side toward the back cover.
5. Push the transmitter halves together.
6. Reinsert the key into the transmitter.

• Replace the battery when the DIC displays REPLACE BATTERY IN REMOTE KEY.
• Do not touch the circuitry, since static could damage the transmitter.
• The battery is not rechargeable.

Source: 2020 Chevrolet Sonic owner's manual, PDF pages 17, 16. 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.