What Battery Does My Key Fob Use?

The vast majority of key fobs run on a small, flat, round coin cell battery, the kind you can find at almost any pharmacy or hardware store. There are several common sizes, and they look very similar but are not all interchangeable. A battery that is slightly too thin can lose contact, and one that is the wrong type will not give the fob the steady power it needs.

Rather than guessing, the safest move is to open the fob and read the marking printed on the old battery, then match it exactly. The number stamped on the cell tells you the size and chemistry, which is all you need to buy the correct replacement.

Your owner's manual usually lists the correct battery for your key, often in the section on remote or smart-key maintenance. If you do not have the manual handy, the old battery itself is the most reliable guide, since the size code is printed right on its face. Take a photo of it before you head to the store so you match it precisely.

Avoid buying purely on price. A fresh, name-brand coin cell of the correct size will give you the best range and the longest life, while a weak or old bargain battery can leave you with the same dead-fob symptoms you were trying to fix. Buy from a store with good turnover so the battery is not already old on the shelf.

Most fobs pop open along a seam, and many hide a small notch for a coin or a flat tool. Some have a slide-out emergency blade that you remove first to reveal the seam. Work gently so you do not crack the case or pry against the circuit board, and note which way the old battery faces so you install the new one the same way.

If your fob will not open, the contacts look corroded, or a fresh battery does not bring it fully back to life, do not force it. A mobile locksmith can open it safely, clean the contacts, test the fob, and program a replacement if the fob itself has failed. If you would rather not risk damaging the key, call us and we can handle it.