Your Subaru access key will show warning signs before the battery dies completely

When your Subaru's key fob battery runs low, the vehicle usually sends you a signal first. You might see a message on your dashboard that says "Key Battery Low" or "Smart Key Battery Low," or the fob straightforward stops working at normal range — you have to stand closer to the car to lock or unlock it. Some owners notice the buttons become less responsive or require harder pressing before the doors respond.

The battery itself is a coin-cell battery, typically a CR2032 or similar small round battery you can buy at any pharmacy, grocery store, or hardware store for a few dollars. Replacing it takes about five minutes and requires no tools beyond what you might already have at home. Subaru does not require you to go to a dealership for this maintenance.

Key Takeaways

  • A low key fob battery shows up as a dashboard warning or reduced range before the fob stops working entirely.
  • The battery is a standard coin-cell type (usually CR2032) that costs a few dollars and is sold at most retail stores.
  • You can replace the battery yourself by opening the fob case, removing the old battery, and inserting a new one in the same position.
  • If you replace the battery and the fob still does not work, the fob itself may need service from a Subaru dealer.
  • A low key battery does not affect your car's main battery or engine — it only powers the wireless lock and unlock functions.

How to identify which battery your key fob uses

Most Subaru key fobs from the past 15 years use a CR2032 battery, but some models use CR2025 or CR2016. The easiest way to know which one you need is to look at your owner's manual — it will list the exact battery type for your model year. If you do not have the manual, you can also open the fob and look at the battery itself; the type is printed on the battery's surface.

To open the fob, look for a small slot or seam on the edge. Most Subaru fobs have a slot where you can insert a coin or flat tool to gently pry the two halves apart. Some fobs have a small button you press to release the case. Once open, note the battery's orientation — which side faces up — before you remove it. This matters because inserting the new battery backwards will prevent the fob from working.

Steps to replace the battery yourself

Start by purchasing the correct battery type from a pharmacy, grocery store, or electronics retailer. Bring your fob with you if you are unsure which type you need, and staff can usually confirm it by looking at the fob or checking your vehicle's year and model.

At home, use a coin or plastic pry tool to gently open the fob case along the seam. Do not force it — if you meet resistance, look for a small button or release mechanism you may have missed. Once the case is open, carefully remove the old battery and note which side was facing up. Insert the new battery in the same orientation, with the positive side (marked with a +) facing the same direction as the old one faced. Close the case until it clicks, and test the fob by pressing the lock and unlock buttons from a normal distance away from your car.

If the fob works when ready after replacement, you are done. If it does not work, try opening the fob again and reseating the battery — sometimes it needs to sit fully in the contact points. If it still does not work after that, the fob itself may have an internal problem and will need service from a Subaru dealer.

When to replace the battery before it fully dies

You do not have to wait until the fob stops working entirely. If you see the dashboard warning or notice the fob only works from very close range, replacing the battery then means you will not be stranded with a non-working fob later. This is especially useful if you travel frequently or live far from a dealership.

Some owners keep a spare CR2032 battery in their car or wallet for this reason. The battery costs so little that buying one in advance costs less than the inconvenience of a fob that fails at an awkward moment.

What a low key battery does and does not affect

A dead key fob battery only stops the wireless lock and unlock functions. It does not drain your car's main battery, affect the engine, or prevent you from starting the vehicle. If your key fob battery is dead, you can still unlock your car using the physical key blade that is usually hidden inside the fob case — slide or pry out the blade and use it in the door lock as you would with an older car key.

You can also start the car by pressing the start button on the dashboard with the fob itself, even if the battery is dead. The car recognizes the fob's presence through a different system that does not rely on the battery. So a low or dead key fob battery is inconvenient but not an emergency.

If the fob still does not work after you replace the battery

If you have replaced the battery with the correct type, inserted it in the right direction, and the fob still does not respond, the fob may have water damage, a broken button, or a faulty circuit board. At this point, a Subaru dealer can diagnose the problem and either repair or replace the fob. Replacement fobs typically cost between $200 and $400 depending on your model year, though some dealers offer refurbished units at a lower price.

Before you visit a dealer, confirm that you are using the correct battery type and that you inserted it correctly. Many fobs that seem broken are actually just reassembled incorrectly. If you are not confident in your replacement, a dealer can also replace the battery for you for a small service fee, usually under $50.

Frequently Asked Questions

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

No. Using the wrong battery type can damage the fob's circuit board or cause it to malfunction. Stick with the type listed in your owner's manual or printed on the old battery. Most stores carry multiple coin-cell types, so the correct one should be straightforward to find.

How long does a key fob battery usually last?

Most Subaru key fob batteries last three to four years with normal use, though this varies based on how often you use the fob and the climate where you live. Extreme heat or cold can shorten battery life. There is no way to predict exactly when yours will die, which is why the dashboard warning is useful.

What if my key fob gets wet — does that ruin the battery?

Water can corrode the battery contacts or damage the circuit board, but the battery itself is usually fine. If your fob gets wet, open it, dry the battery and the inside of the case thoroughly, and reassemble it. If it still does not work after drying, the internal circuitry may be damaged and the fob will need service.

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

No. Replacing the battery does not erase any programming. The fob should work when ready after you insert the new battery and close the case. If it does not, the problem is not the battery replacement itself.

Can I buy a replacement key fob online instead of from a dealer?

Yes, aftermarket and refurbished fobs are available online and are often cheaper than dealer fobs. However, you will need to have a dealer or a may have access to locksmith program the fob to your vehicle, which usually costs $50 to $150. Factor that cost into your decision when comparing prices.