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Key fob battery — check coin-cell printed side before close

Key fob

Before you close a key fob case after a CR2032 swap, match the printed side so key fob not working is not just an upside-down key fob battery.

coin cell printed side polarity before key fob close — related household tip photo
Photo: Gerhard H Wrodnigg / Wikimedia Commons (CC BY-SA 2.5)

A fresh CR2032 only helps if the + printed face matches the tray mark. Confirm polarity before you snap the key fob case so key fob not working after a key fob battery swap is not just an upside-down cell.

Match coin-cell printed side and polarity before the key fob snaps shut

  1. Open the tray and note which side of the old cell faces out — usually the printed + face is visible toward you or toward a + emboss in the plastic.
  2. Set the new CR2032 the same way. Do not rely on “flat side down” folklore; follow the tray mark and the printed face.
  3. Seat the cell fully in the recess so the shell does not pinch the edge when you close the key fob case.
  4. Snap shut and retest lock range before you blame the board or a re-sync.

Honest stop: if the tray has no polarity mark and the old cell was already mixed up, check the service diagram or matching shell kit photo — do not stack two cells or force a bent contact flat.

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