How to Change a Subaru Key Fob Battery

A fresh battery can restore normal locking, unlocking, and remote-start functions when a Subaru key fob has become weak or stopped responding. First identify which fob you have: Subaru has used several designs, and the battery type and case-opening points can differ. Check the owner’s manual or the number printed on the old battery rather than relying on a generic model-year chart.

What You’ll Need

A replacement coin-cell battery that exactly matches the type specified for your fob. Common types include CR1620, CR2025, and CR2032, but these are not interchangeable by assumption.
A small flathead screwdriver, plastic pry tool, or the emergency key, depending on the fob’s design.
A clean, dry work surface and good light. A small container can help keep the emergency key and tiny case parts from rolling away.
Your Subaru owner’s manual, if available, to confirm the battery specification and the correct opening procedure.

Avoid using a large screwdriver or a knife. A tool that is too thick can crack the case, while a sharp blade can slip and injure you or damage the fob. Keep the new battery away from children and pets; coin cells can cause severe injury if swallowed.

Step-by-Step

Identify your fob. Look at its shape and controls, then check the owner’s manual for the battery replacement instructions. Subaru has both remote-head keys and separate smart key fobs, and their cases do not all open the same way. If the manual gives a specific battery number, use it.
Get the matching battery. If the old battery is still installed and visible, note its full code before removing it. Match the code exactly, including the number after “CR.” The battery’s voltage and physical dimensions matter; a similar-looking cell can fit poorly or fail to make contact.
Remove the emergency key if present. On many smart fobs, a release or sliding latch lets you pull out the mechanical key. Set it aside. The opening seam or a small slot may be easier to reach once the key is removed. Do not force the latch; consult the manual if it will not move.
Open the case at its intended seam. Find the small notch or slot indicated in the manual or molded into the fob. Insert the flathead tip or plastic tool gently, then twist just enough to separate the two halves. Work around the seam if needed rather than levering hard in one spot. Avoid pushing the tool deep into the case, where it could damage the circuit board or contacts.
Note the old battery’s position. Before lifting it out, observe which side faces up and how it sits in the holder. The positive (+) side is often marked on the battery, but orientation varies by fob. Take a quick photo if that will help you put the replacement in the same way.
Remove and replace the battery. Ease the old cell out with a fingernail or a nonmetallic tool if possible. Do not bend the holder or scrape its contact. Insert the new cell in the same orientation, pressing it into place gently until it sits flat and secure. Handle the battery by its edges; greasy fingerprints can interfere with clean contact.
Reassemble the fob. Check that no buttons, rubber membrane, or internal pieces have shifted. Align the case halves and press them together evenly around the edges until the seam closes. Reinsert the emergency key and confirm that its latch holds. Do not squeeze harder if the case will not close; reopen it and check for a misaligned part or incorrect battery.
Test the functions. Stand near the vehicle and try lock and unlock, then test other buttons your fob has, such as the trunk or remote start. If the vehicle does not respond, try the fob close to the car and check that the battery is seated correctly. Some Subaru models provide a backup way to start the vehicle when the fob battery is depleted; follow the owner’s manual for that model.

Common Mistakes

Guessing the battery size: Similar coin cells can have different thicknesses. An incorrect battery may not fit, may not contact the terminals, or may put pressure on the case.
Reversing the polarity: If the positive and negative sides are opposite the required orientation, the fob may remain unresponsive. Check the old battery position and any polarity marks in the holder.
Forcing the case open: The case should separate at its designed seam. Excessive twisting can snap plastic clips or damage the circuit board.
Touching or bending contacts: Metal contacts must remain clean and spring-shaped to press against the cell. Do not pry them upward or use a tool to scrape them.
Assuming every Subaru fob is the same: Battery type, case construction, and backup-start procedures vary. A method that works for one key may not suit another.
Discarding the old cell carelessly: Keep used coin batteries away from children and pets, and follow local battery-recycling or disposal guidance.

Tips

Replace the battery when the fob’s range becomes noticeably shorter, buttons respond inconsistently, or a vehicle warning indicates a weak key battery. A warning message may differ by model.
Use a fresh battery from intact packaging and check its expiration or condition. A new-looking cell can still be depleted if it has been stored improperly or for a long time.
Work over a table, and keep the fob away from water, dirt, and static-prone clutter while it is open. Do not wash or spray the circuit board.
Take a photo before removing the battery if the holder’s orientation is unclear. This helps prevent a polarity mistake during reassembly.
Keep a working mechanical key accessible. The emergency key can unlock the door on many models, but the exact procedure differs; check the manual rather than forcing a covered lock cylinder.

Troubleshooting

The fob still does not work: Open it again and verify the battery code, polarity, and seating. Look for a cell that is tilted or a contact that has been pushed out of position. If available, test with another new battery of the exact type.

The case will not snap shut: Check that the battery lies flat and that the rubber button pad and internal pieces are aligned. Confirm that the emergency key is fully in place. Do not clamp or force the shell closed, as that can break the clips.

Only some buttons work: The battery may be making intermittent contact, or a button pad may have shifted while the case was open. Recheck assembly. If the problem continues, the fob may have a damaged button, circuit board, or worn case rather than just a weak battery.

The vehicle still will not recognize the key: Try the fob next to the vehicle and use the model-specific backup start procedure in the owner’s manual. If the fob remains unrecognized with a correct, fresh battery, contact a Subaru dealer or qualified automotive locksmith; the issue may need diagnosis or key service.

The fob was dropped or exposed to liquid: A battery change may not fix physical or moisture damage. Avoid repeatedly pressing buttons if the interior is wet, and seek professional inspection rather than applying heat or household cleaners.

Frequently Asked Questions

What battery does a Subaru key fob use?

It depends on the fob. Several coin-cell sizes are used across Subaru designs, so check the owner’s manual or read the code on the existing battery and match it exactly.

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

Usually, replacing a fob battery does not erase the key’s programming. If the fob stops working despite a correct battery and proper installation, consult the manual or a Subaru dealer before assuming it needs reprogramming.

Can I change the battery without a screwdriver?

Some fobs can be opened with the emergency key or a plastic pry tool, while others have a small slot suited to a flathead screwdriver. Use the method specified for your fob and avoid improvised sharp tools.

How can I tell when the battery is low?

Shorter operating range, inconsistent button response, or a low-key-battery message can be signs. These symptoms can also come from interference, a damaged fob, or a vehicle issue.

Will the car start if the fob battery is dead?

Many Subaru models have a backup starting method, but the steps vary. Follow the instructions in your owner’s manual for the exact vehicle; do not assume the same procedure applies to every model.

Is it safe to handle a coin-cell battery?

Handle it by the edges and keep it away from children and pets. If a coin cell is swallowed or placed inside the body, seek emergency help immediately.

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