Open the key fob case and swap out the old battery

Most Subaru key fobs use a coin-cell battery (usually CR2032, CR2025, or CR2016) that you can replace yourself in under five minutes without tools. The battery sits behind a small door on the back or side of the fob. Look for a slot or seam running along the edge—that is where the case splits open.

Slide your fingernail or a plastic spoon handle into the seam and gently twist to pry the two halves apart. Do not use a metal screwdriver or knife, which can scratch the plastic or slip and damage the circuit board inside. Once the case opens, you will see the battery sitting in a small metal holder, usually held in place by a spring clip on one end.

Note which side of the battery faces up before you remove it—the positive side (marked with a + symbol) should face the same direction when you install the new one. Slide the old battery out from under the clip, then slide the new battery in with the positive side facing the same way. Close the case by pressing the two halves together until you hear or feel a click.

Key Takeaways

  • Subaru key fobs typically use CR2032, CR2025, or CR2016 coin-cell batteries that you can buy at any drugstore or supermarket for two to five dollars.
  • The case opens by prying along the seam with your fingernail or a plastic tool—never use metal, which can damage the fob.
  • The battery sits under a metal clip and must be installed with the positive side facing the same direction as the old one.
  • After closing the case, test the fob by pressing each button to confirm the new battery works before you leave the store or drive away.

Find the right battery size for your Subaru model

Subaru key fobs from the 2000s onward almost always use CR2032, which is the most common coin-cell size. However, some older models and certain trim levels use CR2025 or CR2016 instead. The easiest way to know which one you need is to look at the battery you just removed—the size is printed on the side.

If you do not have the old battery anymore, check your owner's manual, which usually lists the battery type in the key fob section. You can also call your Subaru dealer with your vehicle identification number (VIN), and they will tell you the correct size. Most pharmacies, grocery stores, and big-box retailers stock all three sizes in their watch and battery section, usually near the checkout counter.

Avoid common mistakes when replacing the battery

The most frequent error is installing the battery upside down. The positive side (marked +) must face outward toward the spring clip, not toward the circuit board. If the fob does not work after you close it, open the case again and flip the battery 180 degrees.

Another mistake is forcing the case open too hard, which can crack the plastic or break the clips that hold the two halves together. If the seam does not give way easily, try a different spot along the edge—some fobs have a specific weak point. Do not pry with a metal tool or explore sudden pressure; steady, gentle twisting works better than force.

A third common problem is not fully closing the case. If the buttons feel loose or spongy after you reassemble the fob, the case halves are not seated properly. Open it again and make sure both halves are aligned before pressing them together.

Test the fob before you leave

Once you close the case, press each button on the fob—lock, unlock, panic, and trunk (if your model has one)—to confirm the new battery is working. You should see the car's lights flash or hear the locks click. If nothing happens, open the case again and check that the battery is facing the right direction and sitting fully under the clip.

If the fob still does not work after you flip the battery, the problem may not be the battery itself. Try a different new battery from a different package or brand to rule out a defective cell. If a second battery also does not work, the circuit board or buttons inside the fob may be damaged, and you will need to contact your Subaru dealer for a replacement fob.

Where to buy replacement batteries

CR2032, CR2025, and CR2016 batteries are sold at nearly every pharmacy, grocery store, and big-box retailer in the watch and battery aisle. Walmart, Target, CVS, Walgreens, and Rite Aid all stock them. A single battery usually costs two to five dollars; multi-packs of four or more cost less per battery if you want spares.

Online retailers like Amazon also sell these batteries, but you will wait for shipping. Since the job takes five minutes and the battery costs just a few dollars, buying in person is usually faster and cheaper when you factor in shipping time and cost.

When to replace the battery before it dies

A Subaru key fob battery typically lasts three to four years with normal use. You do not have to wait until the fob stops working to replace it. If you notice the buttons require harder presses than usual, or the fob only works when held close to the car, the battery is running low and a replacement will restore full range and responsiveness.

Replacing the battery proactively means you will never be locked out because the fob died at an inconvenient moment. Many people replace the battery when they change their car's oil or rotate the tires, so the task becomes routine rather than urgent.

Frequently Asked Questions

Can I use a different battery size if I cannot find the exact one?

No. CR2032, CR2025, and CR2016 are different thicknesses and voltages. Using the wrong size may not fit in the holder, or it may fit but not power the fob correctly. Always use the exact size printed on your old battery or listed in your owner's manual.

What if my key fob case will not open?

Try a different spot along the seam—the weak point varies by model year. If you still cannot open it, wrap a rubber band around your fingertip for better grip, or use a plastic guitar pick instead of your nail. Avoid metal tools, which can slip and damage the fob. If the case is truly stuck, a Subaru dealer can open it for you.

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

No. Changing the battery does not erase the fob's programming. Once you install the new battery and close the case, the fob should work when ready without any reprogramming steps.

How do I know if the problem is the battery or the fob itself?

Install a new battery and test all the buttons. If some buttons work and others do not, the circuit board or button contacts may be worn. If no buttons work and a second new battery also fails, the fob likely needs replacement. Contact your Subaru dealer for a new fob.

Can I buy a generic battery or does it have to be a Subaru brand?

Any CR2032, CR2025, or CR2016 battery from any brand works the same way. You do not need a Subaru-branded battery. Generic batteries from drugstores and retailers work just as well and cost less.