Your Subaru key fob will show a low battery warning before it stops working
When your Subaru's access key battery runs low, the vehicle's information display will show a message — usually something like "Key battery low" or a battery icon with a warning. This alert means the battery inside your key fob still has enough charge to lock and unlock the doors and open the trunk, but it will fail soon if you do not replace it. You have a window of days or sometimes weeks to change the battery before the fob stops responding entirely.
The battery inside a Subaru key fob is a small coin-cell battery, typically a CR2032 or CR2025 depending on your model year. These batteries cost between $3 and $8 and are sold at drugstores, supermarkets, hardware stores, and online retailers. You can replace it yourself in under five minutes, or you can have a Subaru dealer or local locksmith do it for you.
If you ignore the warning and the fob battery dies completely, you can still unlock your car using the physical key blade hidden inside the fob, or by using your spare key. The vehicle itself will continue to run normally — the dead fob does not affect the car's battery or engine.
Key Takeaways
- A low battery warning on your Subaru's display means the key fob battery will fail within days or weeks, but the fob still works now.
- Subaru key fobs use CR2032 or CR2025 coin-cell batteries that cost $3 to $8 and are sold at most drugstores and supermarkets.
- You can replace the battery yourself by prying open the fob case, removing the old battery, and inserting a new one — the whole process takes less than five minutes.
- If the fob battery dies before you replace it, you can still unlock the car with the physical key blade inside the fob or with a spare key.
How to open your Subaru key fob and locate the battery
The key fob case is held together by a seam, not screws. Look at the edge of the fob where the two halves meet — you will see a thin line running around the perimeter. Insert a flat object like a coin, a flathead screwdriver, or a plastic pry tool into this seam and gently twist to separate the two halves. Do not force it; if you meet resistance, try a different spot along the seam.
Once the case is open, you will see the battery sitting in a small circular slot. The battery is round and flat, about the size of a dime. Note which side is facing up — the positive side (marked with a + sign) or the negative side (marked with a − sign). This matters when you insert the new battery.
If the battery is stuck, do not pry at it with metal tools, as you can damage the circuit board underneath. Instead, gently push it from the back side of the slot using your fingernail or a plastic tool until it pops out.
Replacing the battery with the correct type
Before you buy a new battery, confirm which type your Subaru uses. Check your owner's manual, or search online for your specific model year and trim level — the manual or a Subaru parts site will list CR2032 or CR2025. Both are common, but they are not interchangeable; a CR2032 is thicker than a CR2025, and using the wrong one may prevent the fob case from closing properly.
When you have the correct battery, insert it into the slot with the positive side facing up — the same direction the old battery was facing. Press gently until you hear or feel a small click, which means the battery is seated in the slot. Do not force it; it should sit flush with the slot.
Close the fob case by aligning the two halves and pressing them together along the seam. You may hear a small click as the case snaps shut. Test the fob by pressing the lock and unlock buttons — the doors should respond when ready. If the fob does not work, open the case again and check that the battery is inserted the correct way and is fully seated in the slot.
When to have a dealer or locksmith replace the battery instead
If you are uncomfortable opening the fob case yourself, or if you have tried and the case will not open without risk of damage, a Subaru dealer can replace the battery for you. The cost is usually $15 to $40 for the service, plus the battery itself. A local locksmith can often do the same work for a similar price and may be faster than scheduling a dealer appointment.
Some Subaru dealers will replace the battery for free if you purchase it from them, though this varies by location. Call your local dealer and ask whether they charge a service fee for battery replacement. If you have a spare key fob, you can also bring only that one in for replacement and keep your main fob at home.
What to do if the fob battery dies before you replace it
If the low battery warning appears and you do not replace the battery, the fob will eventually stop responding to button presses. At that point, you can still unlock the car using the physical key blade stored inside the fob. Most Subaru fobs have a small slot or button on the side or back that releases the blade — consult your owner's manual for the exact location on your model.
Once you have the blade out, insert it into the key slot on the driver's door handle (usually hidden under a small cover) and turn it to unlock the door. You can then start the car normally using the push-button start, as long as the physical key blade is inside the vehicle — the car does not need the fob to run.
If you have a spare key fob, use that one while you replace the battery in the dead fob. If you do not have a spare, a locksmith can cut a new key blade or reprogram a replacement fob for you, though this costs more than a straightforward battery replacement.
Preventing future low battery warnings
Key fob batteries typically last three to four years with normal use, though this varies based on how often you press the buttons. You cannot extend the battery life once it has started to fail, but you can avoid being caught off guard by replacing the battery as soon as you see the warning message.
Keep a spare CR2032 or CR2025 battery (whichever type your fob uses) in a drawer at home so you can replace it when ready when the warning appears. This takes less time than a trip to the store and means you will never be without a working fob. If you have a spare key fob, rotate between the two — using one while the other charges — to spread the battery drain evenly.
Frequently Asked Questions
Can I use a different battery type if I cannot find the exact one?
No. CR2032 and CR2025 are different sizes, and using the wrong one may prevent the fob case from closing or may not fit in the slot at all. Check your owner's manual or call a Subaru dealer to confirm the correct type before you buy. Most drugstores and supermarkets stock both types, so finding the right one is usually straightforward.
Will a dead key fob battery affect my car's battery or engine?
No. The key fob battery and the car's battery are completely separate. A dead fob battery only stops the fob from working — it does not drain your car's battery or prevent the engine from starting. You can still drive and operate the car normally using the physical key blade.
How long does a new key fob battery last?
Most key fob batteries last three to four years with typical use. Heavy use — pressing the buttons many times per day — may shorten this to two years. Light use may extend it to five years or longer. You will receive a low battery warning before the battery dies completely, giving you time to replace it.
What if the fob still does not work after I replace the battery?
First, open the fob again and check that the battery is inserted the correct way (positive side up) and is fully seated in the slot. If it is, the problem may be a damaged circuit board or button contact inside the fob. In that case, a locksmith or Subaru dealer can repair or replace the fob for you.
Can I replace the battery in a key fob while the car is running?
Yes. Replacing the key fob battery does not affect the car's operation at all. You can do it while parked, while driving, or anywhere else. The car will continue to run normally, and you can use the spare fob or physical key blade to lock and unlock the doors.