How To Change Battery On Subaru Key Fob: A Complete Step-by-Step Guide
Changing the battery on your Subaru key fob requires a flathead screwdriver or coin, a replacement CR2032 or CR1632 lithium coin cell, and a few minutes of careful handling to avoid damaging the internal plastic clips and electronic transponder chip. Knowing the exact fob variant—whether standard integrated key, push-to-start smart fob, or older teardown style—ensures you preserve vehicle security synchronization and prevent costly dealership programming fees.
Pre-Operation & Equipment Checklist
Successful execution of a Subaru key fob battery replacement relies on having the correct replacement hardware, appropriate hand tools, and a clear understanding of the fob's internal mechanical layout. Using incorrect cell sizes or unrated tools can deform the casing, compromise weather sealing, or short-circuit the printed circuit board.
- Essential Gear & Tools: Precision flathead screwdriver (1.4mm or smaller), lint-free microfiber cloth, non-conductive plastic pry tool (optional), and OEM-spec replacement lithium coin cell battery.
- Mandatory Prerequisite Knowledge: Identification of specific fob shell generation, understanding of static electricity discharge precautions (ESD), and awareness of vehicle reprogramming requirements if power is disconnected for an extended period.
- Estimated Budget & Duration: Total material cost ranges from three to eight dollars for the battery; total operational duration takes between three and five minutes per key fob.
Step-by-Step Replacement Workflow
Step 1: Extract the Mechanical Emergency Key
Begin by locating the physical metal key release slider or push-button located at the top or base of the Subaru key fob housing. Slide or depress this release mechanism while firmly pulling the metal emergency key blade outward until it completely separates from the main fob body. Set the metal key aside, as its removal exposes the primary chassis release slots needed to split the outer plastic shell.
Pro-Tip: Never force the metal emergency key out without fully engaging the release latch, as doing so can permanently shear the internal spring-loaded retention clip.
Step 2: Separate the Key Fob Outer Shell Halves
Look into the newly exposed cavity left by the extracted emergency key to find a small rectangular or circular notch designed for leverage. Insert the tip of your flathead screwdriver or the edge of a coin into this designated slot and gently twist the tool like a doorknob. The plastic snap-fit seam running along the perimeter of the fob should pop open, allowing you to separate the front and rear shell halves completely.
Warning: Avoid inserting metal tools too deeply into the seam to prevent scratching the integrated circuit board or puncturing the rubber keypad membrane.
Step 3: Extract the Circuit Board and Depleted Battery
Carefully lift the internal rubber pad or the exposed electronic circuit board module out of the lower shell casing if it does not remain seated. Locate the coin cell battery, which is usually held in place by a metal or plastic retention clip. Gently pry the old battery upward from its contact terminal using a small precision screwdriver, taking care not to bend the delicate spring fingers that provide electrical continuity.
Step 4: Install the New Lithium Coin Cell Battery
Verify the polarity markings printed on the circuit board or the battery retention door, ensuring the positive (+) side faces upward (or matches the manufacturer's specific orientation diagram). Slide or press the new CR2032 or CR1632 lithium coin cell into the terminal housing until it clicks securely beneath the retaining tab. Wipe the surface of the new battery with a clean microfiber cloth beforehand to remove skin oils that can accelerate corrosion and discharge.
Step 5: Reassemble the Housing and Test Functionality
Align the front and rear plastic shell halves together, ensuring the rubber weather seal is properly seated within its channel to maintain moisture resistance. Press the two halves firmly along their outer edges until all plastic snap-fit clips lock into place with an audible click. Reinsert the metal emergency key blade into its slot and test the lock, unlock, and panic buttons within range of your Subaru to verify immediate remote transmission.
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Subaru Key Fob Battery Specifications and Compatibility
| Subaru Fob Type | Model Years | Battery Size | Voltage | Common Tool Required |
|---|---|---|---|---|
| Push-Button Smart Fob | 2015 – Present | CR2032 | 3V DC | Small flathead screwdriver |
| Integrated Flip Key | 2010 – 2019 | CR1632 | 3V DC | Coin or 1.4mm driver |
| Standard Remote Head Key | 2008 – 2017 | CR1620 | 3V DC | Precision flathead |
| Older Legacy/Outback Fob | 2005 – 2014 | CR2016 | 3V DC | Plastic pry tool |
Common Site Failures & Field Fixes
Even after installing a fresh battery, users occasionally encounter operational glitches due to minor assembly errors or transient electrical states.
- Root Cause: Remote buttons fail to respond immediately after battery replacement.
- Actionable Fix: The vehicle may need a synchronization cycle. Insert the physical mechanical key into the driver-side door lock, cycle it to the lock and unlock positions twice, and press any button on the remote to re-handshake the rolling security codes with the body integrated unit.
- Root Cause: The plastic housing will not snap completely flush along the edges.
- Actionable Fix: Inspect the internal rubber gasket and circuit board alignment. If either component is pinched over a plastic alignment post, the housing will separate; reposition the internal module so it sits flat in the molding channel.
- Root Cause: The remote works only when standing directly adjacent to the steering column.
- Actionable Fix: Finger oils or low-quality replacement batteries can cause voltage drop. Wipe the battery contacts with isopropyl alcohol on a cotton swab and ensure you are using a fresh, name-brand lithium cell.
Frequently Asked Questions
What size battery does a Subaru key fob take?
Most modern Subaru push-button smart fobs use a CR2032 3-volt lithium coin cell battery, while older integrated flip keys and remote head keys frequently use CR1632 or CR1620 batteries. Always check the stamped code on your old battery before purchasing a replacement to ensure exact physical and electrical compatibility.
Do I need to reprogram my Subaru key fob after changing the battery?
No, changing the battery does not erase the programmed memory or transponder chip stored within the key fob circuit board. The vehicle's immobilizer system retains the key's unique identification code indefinitely, even when completely unpowered for extended maintenance windows.
How do I know if my Subaru key fob battery is dying?
Common indicators of a failing battery include a drastically reduced operational range, intermittent remote response requiring multiple button presses, or a warning message on your instrument cluster stating "Keyless Access System Check Required" or "Key Battery Low."
Can I damage my key fob by using the wrong tool?
Yes, using an excessively wide screwdriver or a sharp knife can crack the delicate plastic casing, strip the leverage notch, or puncture the sealed lithium cell, creating a fire hazard. Always use a precision jeweler's screwdriver or a standard US coin to distribute opening pressure evenly.
What should I do if the red LED light on the fob stays on?
A continuously illuminated LED light usually indicates a short circuit caused by incorrect battery installation or moisture trapped inside the circuit board. Immediately remove the battery, dry the internal components with compressed air or isopropyl alcohol, and reinstall the battery with the positive terminal facing upward.
Keep your Subaru operating seamlessly by stocking up on the correct replacement batteries and maintaining your remote hardware proactively before complete power failure occurs.
