Comprehensive Guide: How To Change A Battery In A Subaru Key Fob
Replacing a dead Subaru key fob battery is a straightforward maintenance task that requires only a flat-head screwdriver and a CR2032 or CR1620 coin cell battery. By carefully releasing the mechanical key and prying the fob housing apart along the seam, owners can restore full remote functionality in under five minutes without specialized diagnostic tools.
Pre-Operation Requirements and Tooling Specifications
Before attempting to open your Subaru key fob, ensure you have the correct battery type and the necessary non-marring tools to prevent aesthetic damage to the plastic casing. Subaru has transitioned through several remote designs over the last decade, primarily utilizing either the CR2032 or the thinner CR1620 lithium coin cell. Confirm your specific remote model by checking the back of the fob or the owner's manual before purchasing replacement components.
- Essential Tools: A precision flat-head screwdriver (ideally 3mm width) or a specialized plastic prying tool to prevent marring the casing seam.
- Replacement Battery Standards: Panasonic, Energizer, or Duracell CR2032 (3-volt) for most newer smart fobs, or CR1620 for older integrated remote-head keys.
- Workspace Requirements: A clean, well-lit, non-magnetic surface to prevent the loss of small internal components or rubber button gaskets.
- Time Allocation: 3 to 7 minutes for a standard replacement.
- Cost Benchmarks: $3 to $8 per battery depending on brand quality and retail location.
Execution Workflow for Subaru Key Fob Battery Replacement
The following steps apply to the most common Subaru "Smart Entry" push-button start fobs. While minor variations exist between the 2015-era teardrop fobs and current-generation proximity keys, the mechanical prying process remains largely consistent.
Step 1: Mechanical Key Extraction
Locate the small release lever or button positioned on the side or bottom of the key fob housing. Press and hold this release while simultaneously pulling the integrated metal emergency key blade outward. Removing this blade is mandatory, as it acts as the primary locking mechanism holding the two halves of the fob shell together.
Step 2: Breaking the Casing Seal
With the mechanical key removed, identify the seam that runs along the perimeter of the fob. Insert your precision flat-head screwdriver into the slot specifically designed for prying, which is usually located near the area where the mechanical key was housed. Gently rotate the screwdriver to create a gap between the two halves. Work the tool slowly around the edges of the fob to disengage the internal plastic clips.
Warning: Do not apply excessive force to a single point. If the housing does not pop open, move to an adjacent spot along the seam to distribute pressure, preventing the plastic locking tabs from snapping.
Step 3: Circuit Board and Battery Extraction
Once the casing is separated, you will see the rubber button pad, the internal circuit board, and the coin cell battery secured by a metal clip. Lift the circuit board carefully—ensure it does not fall out of the housing, as the rubber gaskets beneath the buttons can become misaligned. Use your flat-head screwdriver to gently slide the old battery out from under the metal retaining tab.
Step 4: Installation and Sealing
Orient the new battery so the positive (+) side faces upward (or matches the polarity indicated on the battery cradle). Slide the new battery into position until it clicks firmly under the metal tab. Before reassembling, wipe the contact points with a clean, dry microfiber cloth to remove oils. Align the two halves of the fob shell, press them firmly together until you hear an audible snap from the clips, and reinsert the mechanical emergency key.
Subaru Forester Key Fob Battery
Technical Specifications and Battery Compatibility Matrix
Understanding the physical and electrical differences between the two common Subaru key fob battery types is critical for ensuring reliable remote signal transmission and preventing premature discharge.
| Battery Specification | Voltage Rating | Typical Diameter | Primary Application |
|---|---|---|---|
| CR2032 | 3.0 Volts | 20.0 mm | Modern Smart Proximity Fobs |
| CR1620 | 3.0 Volts | 16.0 mm | Older Remote-Head Keys |
| Chemistry | Lithium Manganese | Non-Rechargeable | Primary/Secondary Entry |
Troubleshooting Common Remote Entry Failures
If the remote fails to operate the vehicle locks or ignition after the battery replacement, verify these common error states.
- Incorrect Battery Polarity: If the battery was installed upside down, the circuit will remain open. Open the fob, confirm the positive (+) side faces the printed mark on the contactor, and reseat the battery.
- Oxidized Contact Points: If the fob was exposed to moisture or extreme humidity, the metal contact tabs may have developed a layer of oxidation. Gently scrape the surface of the contact points with a dry cloth or an eraser to restore conductivity.
- Desynchronization Events: In rare instances where the battery is dead for an extended period, the fob may lose its rolling code sync with the vehicle’s Body Control Module. If the fob remains unresponsive after a successful battery swap, hold the fob directly against the Start/Stop button while pressing it to initiate an emergency bypass start, which often triggers a re-sync.
Frequently Asked Questions
Will my car alarm go off if I open the key fob?
No, the key fob is a passive device. Opening the plastic shell and removing the battery will not trigger the vehicle's security system. The vehicle only reacts to encrypted signals sent from a functioning, synced remote.
How do I know if my Subaru key fob battery is actually dead?
Common indicators include the need to hold the remote closer to the door handle to unlock the vehicle, intermittent responsiveness, or a "Key Battery Low" warning displayed on your Subaru's instrument cluster multi-function display.
Can I damage the circuit board during the process?
While the circuit board is resilient, it is sensitive to static electricity and physical pressure. Avoid touching the gold-plated contact points with bare fingers if possible, and never use sharp metal objects to pry the board itself, as this can cause short-circuits.
Do I need to reprogram the fob after replacing the battery?
Under normal conditions, Subaru proximity fobs retain their memory through battery changes. Reprogramming is only necessary if the fob has been subjected to significant physical trauma or if the vehicle’s security module has been reset.
Secure Your Subaru’s Performance and Reliability
Maintaining your key fob is just one piece of the puzzle in ensuring your Subaru remains the reliable vehicle you depend on every day. Consult your local Subaru authorized service center for diagnostic testing if remote issues persist beyond a simple battery replacement.
