CR2025 Key Fob Battery Replacement: Step-by-Step Guide

To replace a CR2025 key fob battery, open the case, note which side of the old battery faces up, lift it out with a plastic tool, fit a new CR2025 the same way, close the fob and test the buttons. The CR2025 is a 3-volt lithium coin cell, 20 mm wide and about 2.5 mm thick, used in slimmer fobs where a thicker CR2032 would not fit. The job takes about five minutes.

CR2025 key fob battery specs

The CR2025 and CR2032 share the same diameter and voltage, so they are easy to confuse. The difference is the thickness and the capacity. Our comparison of CR2032 vs CR2025 explains whether you can swap them, and the size chart lists other sizes.

What you need

• A new CR2025 battery from a recognised brand.
• A small plastic pry tool, a guitar pick or a coin.
• A small Phillips screwdriver, if the fob has a screw.
• Your phone to photograph the old battery.
• A soft cloth and a clear table.

How to replace a CR2025 key fob battery

1. Check the code. Make sure the old battery says CR2025, or that the manual calls for it. The thickness matters in slim fobs.
2. Open the fob. Look for a seam notch, a screw, a release button or a sliding cover. See how to open a key fob without breaking it for the common designs.
3. Photograph the battery. Note which way the printed (+) face points. The polarity guide explains how to tell the sides apart.
4. Remove the old battery with a plastic tool. Avoid metal screwdrivers, which can bend the contacts.
5. Fit the new CR2025 by the edges, with the printed face in the same direction as before.
6. Close the case until every clip clicks, then test lock, unlock and the other buttons beside the car.

Why some fobs use a CR2025

Fob designers choose a battery size to match the case. A slim fob with a thin battery tray fits a CR2025, while a bulkier case has room for a CR2032. The CR2025 trades capacity for thickness: it carries less energy, so in a similar fob it normally runs out sooner. That is not a problem if the fob is designed for it, but it is a good reason to replace it on schedule. See how often to replace a key fob battery.

Can you use a CR2032 instead of a CR2025?

Usually not. A CR2032 is 0.7 mm thicker, so it may stop the case closing, press hard on the contacts, or crack the plastic. If the cover closes without any pressure it may work for a while, but it is a workaround. Always buy by the code printed on your old battery. If you only have the other size in an emergency, use it to get through the day and buy the right one afterwards.

CR2025 or CR2016? Do not mix them up

A CR2016 is the same width (20 mm) but only 1.6 mm thick, so it looks like a thin CR2025. A CR2016 fits a fob made for a CR2025 only loosely, giving a poor contact and short life. Check the code stamped on the battery rather than judging by the look, and if the print has worn off, a caliper reading of the thickness settles it: about 2.5 mm for a CR2025, 1.6 mm for a CR2016, and 3.2 mm for a CR2032.

How to measure a battery if the code is unreadable

1. Use a digital caliper, or a ruler if you do not have one.
2. Measure across the flat face for the diameter. 20 mm means the first two digits are 20.
3. Measure the edge for the thickness. About 2.5 mm points to a CR2025.
4. Compare with the size chart and buy that code.

OEM or aftermarket CR2025?

You do not need a battery with a car-maker logo. A reputable branded lithium CR2025 gives the same 3 V and similar capacity. The risk is not “aftermarket” but poor-quality unbranded cells that may not hold their stated capacity, or old stock that has sat on a shelf for years. Buy from a seller that turns over stock quickly, and check the date on the pack.

Fobs with two CR2025 cells

Some fobs use two batteries. If yours has two, replace both at the same time with the same type. The old cell drags down the performance of the new one, and you may end up opening the fob again a few weeks later. Photograph the layout first, because the two cells may face different ways.

Storing and keeping a spare

Keep spare CR2025 cells in their original blister pack at room temperature, away from coins and other metal that can touch both faces and drain them. Do not leave them in the car. A written date on the pack helps you use the oldest first.

How long the job takes and what it costs

Once you know how your fob opens, the whole job takes around five minutes. A single battery usually costs only a few dollars, and a multi-pack costs more per pack but less per cell. Shops and dealers may charge a labour fee on top, which is the main reason many owners change the battery themselves.

Signs your CR2025 is weak

• You need to be closer to the car for the fob to respond.
• You have to press a button more than once.
• The fob works some days and not others, especially in cold weather.
• The LED, if there is one, is dim.
• The car shows a low key battery message, or fails to detect a smart key.

Because a CR2025 has less capacity, these signs may appear sooner than in a CR2032 fob. Our guide to key fob battery life explains how long to expect.

Tips for a good fit in a slim fob

• Make sure the battery sits flat and under the clip. A tilted cell causes a loose contact.
• Do not stack two thin cells to “make up” thickness. That is unsafe and unreliable.
• If the fob rattles or the battery feels loose, check that you have a CR2025 and not a thinner CR2016.
• If the contact has flattened, lift it gently with a plastic tool to restore pressure.
• Check the case closes without force.

Common mistakes

• Putting the battery in upside down.
• Choosing a CR2016 or CR2032 because it “looks the same”.
• Handling the battery by its flat faces.
• Prying with a big metal screwdriver.
• Leaving the old battery where a child can reach it.

If the fob still does not work

1. Check the direction and that the battery is seated under the clip.
2. Clean the contacts with a dry cloth.
3. Try a different CR2025, since a battery can be flat out of the pack.
4. Test the spare fob.

Then read what to do when a new battery did not fix the problem and whether a fob needs reprogramming. If you are unsure whether to do the job yourself, see can I replace a key fob battery myself?

Buying a CR2025

• Choose a branded lithium CR2025 and check the expiry date on the pack.
• Do not buy rechargeable cells, which run at a different voltage.
• A two-pack gives you a spare.
• Keep spares at home, away from metal objects.

You can browse CR2025 batteries on Amazon. As an Amazon Associate, ReplaceKeyFob earns from qualifying purchases; see our disclaimer.

Disposing of the old battery

Do not throw a used coin cell loose in the bin. Cover both faces with clear tape, and take it to a battery recycling point, which many shops and local recycling centres offer. Keep it out of reach of children until then.

Frequently asked questions

How do I replace a CR2025 battery in a key fob?

Open the case, note the battery direction, remove the old cell with a plastic tool, insert the new CR2025 the same way up, close the case and test.

What is the difference between CR2025 and CR2032?

Both are 3 V and 20 mm wide, but the CR2025 is about 2.5 mm thick with less capacity, and the CR2032 is about 3.2 mm thick.

Which side of a CR2025 is positive?

The flat face with the printed text. Match the direction of the old battery.

How long does a CR2025 last in a key fob?

Often one to a few years, depending on use. It usually runs out a little sooner than a CR2032 in a similar fob.

Can I use a CR2032 in a CR2025 fob?

Not recommended. It is thicker and may not fit or may strain the contacts.

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

Normally not.

Where can I buy a CR2025?

Electronics shops, supermarkets, pharmacies and online sellers. Check the expiry date.

Bottom line

A CR2025 swap is quick if you match the code, copy the direction and use plastic tools. Use the thinner cell only where the fob was designed for it, and keep every coin cell away from children.