How to Change Subaru Key Battery: Check These First

To change a Subaru key battery, first match the model year, fob type, and battery code printed on the installed cell; then remove the emergency key, open the access-key case at its gap with a cloth-wrapped flat screwdriver, replace the CR2032 with the positive (+) side facing up, snap the case shut, and test both the buttons and touch-handle entry. Those are Subaru's steps for the 2023 Forester access key. A traditional keyed transmitter in the same manual uses a CR1620 with the negative side up.

The cell swap takes little time. Identification is where people get caught. Subaru used more than one key design, and search results often collapse “Subaru key” into a single object. That is how a plausible CR2032 can land in a fob whose own manual calls for a CR1620.

I approach the job as I would a mismatched caffeine panel on a dented can: read the physical item before trusting the sales sheet. I once let a distributor sheet outrank a can and had to correct the item. An online battery listing is the distributor sheet here. The old cell, fob case, vehicle year, and Subaru manual are the package in your hand.

What has to be true before you open the fob?

You should be able to identify your Subaru by model year and identify the device as either an access key with a removable emergency key or a traditional transmitter built into a keyed head. You should also have a dry, clean work area, a small flat-head screwdriver, tape or cloth for its tip, and a replacement whose code matches the installed battery and owner's manual.

Use the year printed on the vehicle registration or the certification label, rather than the purchase year. For a Subaru Forester key fob battery replacement, Subaru's Vehicle Resources selector asks for model year, model, and trim before it serves the manual. The same discipline applies to a Subaru Outback key fob battery replacement or Subaru Impreza key fob battery replacement.

Here is the distinction that matters before the case separates:

| Item in front of you | Identifying feature | Battery direction in the 2023 Forester manual | What the battery powers | |---|---|---|---| | Access key fob | Push-button-start fob with a removable emergency key | CR2032, positive (+) side up | Remote buttons and proximity/keyless-access communication | | Traditional remote transmitter | Buttons are part of a key head with an exposed metal key | CR1620, negative (−) side up | Remote lock, unlock, rear-gate, and panic functions | | Vehicle battery or keyless-access hardware | Located in the vehicle, not inside the handheld fob | The coin-cell instructions do not apply | Vehicle electrical supply, antennas, receivers, and control modules |

For one documented anchor, I use the 2023 Forester Limited and Subaru owner's-manual file MSA5M2302A_STIS-Opt. Subaru's parts catalog identifies 88835FL03A as a genuine keyless-entry transmitter number and lists 88835FL030 and 88835FL03B as superseded numbers for that transmitter family. Part revisions and button layouts vary, so use the VIN when buying an entire fob. You do not need a new transmitter number merely to buy its coin cell.

One more precondition: the plastic cover, circuit board, and metal contacts must still be present and seated. Subaru warns against touching or damaging the printed circuit board and against letting dust, oil, or water enter the fob. If the shell is cracked or a contact has detached, a battery-only repair is already the wrong job.

Which battery belongs in your Subaru key?

The 2023 Subaru Forester owner's manual specifies a CR2032 or equivalent for the access key fob and a CR1620 or equivalent for the traditional remote transmitter. For the CR2032, Panasonic Energy's February 2026 specification sheet gives a 3 V nominal voltage, a maximum diameter of 20.0 mm, and a maximum height of 3.2 mm. Energizer's product sheet independently lists 3.0 volts and the IEC designation CR2032.

That installed code is your final check. Open the case gently, read “CR2032” or “CR1620” on the old cell, and compare it with the year-specific manual. If the two disagree, pause. A prior owner may have fitted the wrong cell, or you may be reading instructions for another fob design. Photograph the open case and ask a Subaru parts counter to verify it by VIN.

Do not choose by voltage alone. CR2032 and several other lithium coin cells are nominally 3 V; their dimensions and fit differ. A cell that sits loosely, bows the cover, or needs force has failed the fit check even before you press a button.

How do you change a 2023 Subaru Forester access-key battery?

Subaru's five illustrated operations become six practical steps once identification is included. Work over a tray or light-colored towel so the emergency key and any loose part cannot disappear into carpet.

1. Identify the fob and cell. Confirm that you have the access-key design shown in the 2023 Forester manual. Obtain one new CR2032. Touch a grounded metal object first to discharge static electricity, as Subaru directs.
2. Remove the emergency key. Press the release button on the back of the fob and pull the metal emergency key straight out. Set it where it cannot roll away.
3. Open the case at the intended gap. Wrap the tip of a small flat-head screwdriver with vinyl tape or a cloth. Insert it into the gap revealed at the emergency-key end and twist gently. Do not drive the tool toward the circuit board.
4. Lift out the old cell. Use the protected screwdriver at the battery edge. Before moving anything else, note the printed code and photograph the battery, contacts, and surrounding plastic. Avoid bending the terminals.
5. Install the new CR2032 positive-side up. Subaru's illustration and text place the marked positive (+) face upward in this access key. Seat the edge under its retainers and press it flat without forcing it.
6. Close the cover and test. Align the projections and recesses, then press around the seam until it is even. Reinsert the emergency key. Check a remote button and the passive door-handle function before leaving home with the fob.

No reprogramming step appears in Subaru's battery-replacement procedure. The fob remains registered to the vehicle when only the coin cell is changed. If the case will not close flush, reopen it and inspect the cell seating; squeezing the halves together can bend a contact or crack a locating tab.

Owners searching for a 2023 Subaru Forester key fob battery replacement can stop at step six if both tests pass. Owners with the keyed transmitter should follow their own section of the manual: that procedure opens the key head, removes the transmitter case, releases its hooks, and installs a CR1620 with the negative side facing up.

What result proves the replacement worked?

A passing test checks two radio functions at two distances. First, stand beside the vehicle and use passive keyless access: with the fob in hand or a pocket, grip the front-door handle to unlock, then touch the door-lock sensor to lock. The 2023 Forester manual defines the antenna's passive operating range as approximately 16 to 32 inches (40 to 80 cm).

Then test the remote button from about 30 feet (10 meters), the operable distance Subaru specifies for the remote keyless-entry system under suitable environmental conditions. One press of the lock button should lock the doors, rear gate, and fuel-filler lid and produce one electronic chirp. The hazard lights should flash once when that owner-selectable feature is enabled.

Record the result plainly: “pass at the handle; pass at 30 feet; one chirp; one flash.” If the button works only beside the car, repeat in an open area because buildings, radio transmitters, phones, metal objects, and other fobs can reduce range. If passive entry fails while the 30-foot button test passes, the new cell is transmitting; the remaining fault is more likely in proximity detection, settings, or vehicle hardware.

What does Subaru's low-battery warning actually say?

In the 2023 Forester owner's manual's warning table, the exact status wording is “The battery of the access key fob is low.” The prescribed action is “Replace the battery of the access key fob.” The same row specifies one interior “Ding” and no outside warning chime.

Some dashboards and owner reports abbreviate the idea as “Access Key Battery Low.” Treat the year-specific manual wording as the verified text for the 2023 Forester. Subaru also says an access-key battery lasts approximately one to two years, depending on operating conditions, because the fob continuously communicates with the vehicle.

Why can a new coin cell fail to restore keyless access?

A fresh coin cell does not repair every failure that looks like a weak fob. The fastest diagnosis uses comparison: test both functions, test the spare fob, and observe whether the vehicle has other low-voltage symptoms.

| Test pattern after replacement | Stronger suspect | Reason | |---|---|---| | One fob fails both tests; the spare passes | Failed cell fit, bent contact, damaged board, or failed fob | The same vehicle antennas and receiver work with the spare | | Remote buttons pass at 30 feet; passive handle entry fails | Disabled keyless-access setting, interference, or proximity-system fault | The fob can transmit remotely, but the short-range exchange is failing | | Both fobs have poor remote range in the same location | Environmental interference or vehicle receiver/antenna issue | Two independent coin cells showing the same location-specific result shifts suspicion to the shared path | | Both fobs fail and the vehicle shows broader electrical trouble | Vehicle 12 V battery, connection, or vehicle electronics | The handheld CR2032 cannot restore power to the car's receivers and modules |

The 2023 Forester manual supplies a useful boundary between those last two batteries. After the vehicle battery has been discharged or replaced, the steering-lock system may need initialization: switch the ignition off, open and close the driver's door, and wait approximately 10 seconds. That procedure has nothing to do with seating a CR2032 inside the fob.

Inspect the simple things before buying hardware. Confirm the new cell's positive face is up in an access fob, the metal contacts touch it, and the case is fully seated. Try the spare key away from chargers, laptops, phones, and large metal objects. If an orange push-button operation indicator flashes for up to 15 seconds, Subaru classifies that as a system-malfunction warning and directs the owner to a dealer.

Frequently asked questions

What kind of battery does my Subaru key need?

It depends on the fob design and model year. The 2023 Forester owner's manual specifies a CR2032 for the push-button-start access key and a CR1620 for the traditional keyed transmitter. Read the installed cell and verify it against Subaru's manual for your year, model, and trim before buying a replacement.

How do I open up a Subaru key fob?

For a 2023 Forester access key, press the release button and remove the emergency key. Wrap a small flat-head screwdriver with vinyl tape or cloth, insert it into the gap at the emergency-key end, and twist gently. Subaru warns against damaging the circuit board or letting dust, oil, or water inside.

Can I replace my Subaru battery myself?

You can replace the key-fob coin cell yourself by following the year-specific owner's manual; the 2023 Forester procedure uses basic hand tools and requires no reprogramming. A Subaru vehicle's 12 V battery is a separate job with different hazards, connections, and possible initialization steps. Do not apply coin-cell instructions under the hood.

What battery type does a Subaru key fob use?

Many Subaru access keys use a 3 V CR2032 lithium coin cell, including the 2023 Forester access key documented by Subaru. Some traditional keyed transmitters use a CR1620 instead. The Subaru badge does not determine the cell: the fob design, model year, installed battery marking, and owner's manual do.

What should I do if a Subaru key-fob spring falls out?

Stop assembly, keep the spring and fob together in a small bag, and photograph where it fell from. Subaru's 2023 Forester access-key battery procedure does not direct you to remove a spring. A loose battery-contact spring or key mechanism needs correct positioning; have a Subaru parts counter or automotive locksmith inspect it before applying power.