How to Change a Key Fob Battery

Reviewed June 2026 by GarageDex editorial

GarageDex's step-by-step guide covers the two things that go wrong with this two-minute job: cracking the case because the pry point was in the wrong place, and buying the wrong coin cell because CR2032 and CR2025 look identical from the top. Most fobs need no reprogramming afterwards, and the ones that do usually re-pair with a single press of the lock button.

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Step by step

Look up the coin cell your fob takes (CR2032, CR2025, CR2016 and CR1620 are the common ones) for your year, make and model.
Release the mechanical key blade if the fob has one: slide the small latch on the back and pull the key out. The slot it leaves is usually the pry point.
Insert a coin or a plastic pry tool in the seam or slot and twist gently to split the two halves. Work around the seam rather than forcing one spot.
Note which side of the old cell faces up (the + marking is usually visible), then lift it out with a fingernail or the pry tool.
Drop the new cell in the same way up, handling it by the edges. Snap the halves together, refit the key blade, and test lock and unlock from a few steps away.

Get the right cell first

The size is printed on the old cell, but you cannot read it until the fob is open, and by then you have already made the trip. Look up the coin cell for your exact year, make and model and buy a sealed pack. If your fob takes two cells, replace both.

What you need

A coin or a small flat screwdriver works for most fobs, but a plastic pry tool is kinder to the plastic and leaves no marks. Handle the new cell by its edges: skin oil on the flat faces raises contact resistance.

Tools used in this guide

Plastic pry tool setSplits the fob at the seam without gouging the caseView on Amazon
Coin cell battery testerChecks the old cell and the new one before you close the fobView on Amazon

These tools fit any vehicle. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you.

Opening the fob without breaking it

Almost every fob has a designed pry point: a notch on the edge, or the slot left when the emergency key is removed. Start there, twist rather than lever, and once the seam opens a little, slide the tool along it. Fobs that are glued or screwed (rare) usually have a visible screw under a label.

If the car says the key is not detected

Most push-button-start cars have a backup spot where the fob still works with a dead battery: hold it against the start button or a marked area on the steering column while pressing start. That gets you home. Then change the cell.

Frequently asked

What battery does my key fob take?

Most use a 3-volt lithium coin cell: CR2032 is the most common, followed by CR2025, CR2016 and CR1620. The number encodes the size (20 mm wide, 3.2 mm thick for a CR2032), so a CR2025 is thinner and can lose contact in a CR2032 fob. Check your exact model rather than guessing from the shape.

Do I need to reprogram the key fob after changing the battery?

Usually no. The fob's pairing lives in the car, not in the fob's battery. If it does not respond after a battery change, first confirm the cell is the right size and the right way up, then press lock or unlock a few times near the car. A few makes want the fob held against a marked spot on the steering column or start button to re-sync.

Why does my key fob still not work with a new battery?

The most common causes, in order: the cell is upside down, the wrong thickness so it is not making contact, the contacts inside the fob are bent or corroded, or the new cell was old stock and already weak. Coin cells lose charge sitting on a shelf, so buy from a sealed pack with a date.

How long does a key fob battery last?

Typically 2 to 4 years. Smart keys that talk to the car constantly (keyless entry and push-button start) drain faster than simple remotes. A shrinking range, needing to press twice, or a dashboard message about the key battery are the early signs.

Need your car's exact spec?

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