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Coin-cell sizes for car remotes

Key fob

Tell CR2032, CR2025, and CR1632 apart, match polarity, and avoid a thinner cell that sits loose in the tray.

coin cell sizes for car remotes — related household tip photo
Photo: Gerhard H Wrodnigg / Wikimedia Commons (CC BY 2.5)

Car remotes almost always use a lithium coin cell. The size is printed on the face of the battery. Mixing sizes is a common reason a “new” battery still fails from two steps away.

Common markings

Marking What to know
CR2032 Thick everyday cell for many flip keys and remotes
CR2025 Same diameter, thinner — can sit loose in a 2032 tray
CR1632 Smaller diameter; used in compact remotes
A27 / tiny AAA-style Older fobs; not a coin cell

Match the marking exactly. A CR2025 in a CR2032 clip may lose contact when you press a button. A CR2032 forced into a thinner tray can bow the cover.

Swap without losing orientation

  1. Photograph the open board so polarity and the metal clip layout are obvious.
  2. Note which face shows + before you lift the cell; in most trays the plus side faces the clip.
  3. Use a plastic pry tool or fingernail in the factory slot — not a deep metal screwdriver on the board.
  4. After the new cell clicks in, wait a minute and test from a few steps away. Some remotes need a short wake-up before range returns.

If a confirmed correct fresh cell still leaves mushy or dead buttons, the pad or board is worn — see Sticky buttons or a cracked key-fob case. For the broader battery-vs-dead-fob decision tree, start with Is it the battery or a dead fob?.

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