How to Replace Subaru Key Fob Battery and Make Sure It Works

To replace the battery in a Subaru key fob, start by identifying the fob style so you open the correct side of the case. Then read the old cell’s marking, install a new coin cell with the same polarity, snap the shell shut, and test lock, unlock, panic, and start functions right away. If the fob still fails after that, the problem is usually the battery fit, the contacts, or the fob itself rather than the car.

Quick answer: identify the fob style before you pry

Before you open anything, figure out which Subaru fob you have. That keeps you from prying at the wrong edge and cracking the shell.

• Separate key-entry fob: a remote with buttons and, on some models, a removable spare mechanical key.
• Smart/proximity fob: a proximity key used with push-button start.
• Combined style: a fob that mixes remote buttons, a hidden key blade, or both.

Here’s the practical reason to start here: Subaru fobs don’t all open the same way, and the battery position can change with the case design. If your fob has a spare mechanical key, remove it first if the design calls for that. On some Subaru keyless entry fobs, that step reveals the release point. If you’re unsure, stop and compare the case to the owner’s manual or the old battery marking before forcing the shell.

If the style is still unclear, match the shell shape and release point to the owner’s manual before you try to pry it apart.

What you need before you start

You only need a few simple things to replace a Subaru key fob battery safely. Have the exact coin-cell size ready, a small flat tool, and a clean work surface with good light.

• The replacement coin-cell battery, matched to the old marking when possible.
• A small flat plastic pry tool, or a small flat screwdriver if you work carefully.
• Clean hands or clean gloves, so oil and dirt do not get into the contacts.

Many Subaru fobs use a coin-cell battery such as CR2032 or CR1620, but do not assume the size from memory. Read the marking on the old battery once you open the case, or check the current Subaru documentation for your exact fob if the old cell is unreadable. That step saves you from buying the wrong battery and opening the shell twice.

Step 1: find the seam and release point

Look for the fob case seam first, not the buttons. On many Subaru remote shells, the safest opening point is near the key-ring side or near the slot where the backup key comes out.

1. Hold the fob in your hand and trace the seam around the edge.
2. Look for a small notch, latch, or split line near the key-ring end or key-blade release area.
3. If the backup key is removable, remove it first and check whether that reveals the actual release point.

If the release point is not obvious, do not pry at random around the buttons. Subaru fobs usually resist because you have not found the latch yet, not because they need force. When the shell will not budge, stop and reassess the seam before you crack a clip.

Step 2: open the case without bending clips

Separate the shell gently and evenly. The goal is to release the clips, not to twist the plastic until it gives.

1. Insert the flat tool at the seam or release notch.
2. Wiggle slightly until you feel the latch give way, then work along the edge a little at a time.
3. Lift the halves apart evenly so one side does not bend the internal clips.

Keep track of any small parts, including the backup key or any tiny insert that comes free with the shell. If the case feels like it is binding, back out and try a different point on the seam. A hard pry is the usual way people break Subaru key fob reassembly before they even reach the battery.

Step 3: remove the old battery and note polarity

Lift the old coin cell out carefully and look at how it sits before you throw it away. The side facing up tells you the polarity you need to match on the replacement.

1. Note which marking is visible on the old cell, since that helps identify the battery type.
2. Lift the battery out with the tool or your fingers if it comes free easily.
3. Save the old cell long enough to compare the size and orientation.

On most coin cells, the marked side is the positive side, but do not rely on memory if the fob design makes the orientation hard to see. Read the battery number now, because that is the cleanest way to tell whether you need a CR2032, CR1620, or another coin-cell battery. If the battery is stuck, do not dig under it hard enough to gouge the contact or battery tray.

If the battery is stuck or shows white, crusty, or green corrosion, stop and clear the loose buildup first. A battery that has leaked or welded itself to the tray can bend the contact if you try to lever it out too aggressively. If the cell will not lift cleanly, use the flat tool from the edge, not the middle, and work slowly until it releases.

Step 4: install the new battery and check contact tension

Put the replacement battery in the same orientation as the old one and make sure it sits firmly in the contacts. A coin cell can look seated and still fail if one spring contact is not pressing the edge well enough.

1. Match the positive and negative sides to the old battery’s orientation.
2. Press it into place until it sits flat in the tray.
3. Check that the contacts touch the battery edge and do not look bent away from it.

If you see corrosion, wipe it away gently only if it is light and dry. If the contacts are bent, carefully bring them back to a shape that presses on the battery edge without scraping through the cell wrap. The battery should not rock, lift, or sit crooked when you let go. If it does, remove it and reseat it instead of forcing the case closed over a bad fit.

Step 5: close the fob until it sits flush

Reassemble the shell with the halves aligned before you press them together. If the clips are lined up correctly, the case should close without a fight and the seam should sit even all the way around.

1. Align the halves so the buttons, battery tray, and any key blade slot line up.
2. Press the shell together evenly around the edge.
3. Check that the seam is fully snapped shut with no gaps or loose corners.

If one side stays proud or the seam will not close flush, stop and reopen it. A clip is probably out of alignment or the battery is not seated fully. Do not force the last corner closed; that is how the shell cracks after an otherwise easy battery swap.

Step 6: test the fob at the car and from a distance

Test the fob right away, before you trust it on the road. You want to confirm the remote buttons work, and if you have a proximity system, that the car still recognizes the fob for starting.

1. Stand near the car and press lock, then unlock.
2. Press panic briefly to confirm the alarm function, then turn it off right away.
3. If your Subaru uses push-button start, test the proximity key behavior at the driver door and at the start button.

Check the buttons from a normal walking distance too, not just when you’re standing right next to the car. Some proximity systems can still start the car with a weak battery while the remote buttons fail first, so you want stable behavior in both modes. If the fob works nearby but not at a normal distance, or the start function is inconsistent, treat that as a warning sign that the battery may not be seated well or the fob needs more attention before you rely on it.

If it still doesn’t work, check these next

If the Subaru remote not working problem continues after the battery swap, the cause is usually one of a few plain things. Start with the battery size and polarity, then move to the contacts and the case fit.

• Wrong battery size: compare the old cell marking or the owner’s manual.
• Reversed polarity: pull the battery and match the orientation exactly.
• Weak contact pressure: a bent spring or flat contact may not be touching the battery edge.
• Corrosion or dirt: clean light buildup carefully; heavy corrosion can mean the fob needs parts or replacement.
• Fob problem, not battery problem: if the shell is closed correctly and the battery is right, the electronics may be failing.

If the case does not sit flush after reassembly, open it again and look for a clip out of alignment or the battery sitting crooked. If your Subaru has push-button start and the fob still reports a low battery after a fresh cell, the issue may be inside the fob rather than in the coin cell itself. At that point, check the exact Subaru documentation for your model or use qualified help before you keep forcing the shell.