How To Change The Battery In Your Subaru Key Fob: A Complete Step-by-Step Guide

To change the battery in a Subaru key fob, release the metal emergency key, insert a flathead screwdriver wrapped in a microfiber cloth into the designated pry slot inside the key cavity, and gently twist to split the housing. Replace the depleted 3-volt lithium cell (typically a CR2032 or CR1632) with a premium new battery, ensuring the positive (+) side faces the correct direction, and snap the casing back together. This entire maintenance process requires no reprogramming and can be successfully completed at home in under five minutes.

Essential Subaru Key Fob Diagnostics, Tools, and Battery Specifications

Modern Subaru key fobs act as complex transponders that continuously communicate with your vehicle’s Keyless Access System. When the internal voltage of the coin-cell battery drops below a critical threshold (typically around 2.7 volts for a nominal 3V battery), the vehicle’s onboard diagnostic system will register the drop. You will notice several distinct operational symptoms indicating it is time for a replacement.

Diagnostic Signs of a Failing Fob Battery

• Decreased Transmitter Range: You must stand significantly closer to your Subaru (within a few feet) to unlock or lock the doors.
• Delayed Response Times: Pressing the lock, unlock, or liftgate buttons results in a noticeable 1-to-2 second delay before the vehicle responds.
• Dashboard Warning Indicator: Many modern Subaru models (such as the Outback, Forester, and Crosstrek) will display a key icon flashing green or amber on the instrument cluster, or output a text warning stating "Key Battery Low."
• Intermittent Proximity Access Failures: The touch-sensitive sensors on the front door handles fail to lock or unlock the car consistently when the key is in your pocket.

Pre-Procedure Equipment and Budget Checklist

Before attempting to open the key fob casing, gather the proper tools to avoid marring the plastic housing or damaging the internal Printed Circuit Board (PCB).

• Replacement Battery: You will need a high-quality 3-volt Lithium coin cell. Subaru smart keys (push-button start) manufactured from 2015 to the present typically require a CR2032 battery. Older integrated-key fobs (standard ignition key) or older remote heads typically require a CR1632 or CR1620 battery. Verify your exact key style in the specification matrix below.
• Precision Pry Tool: A small flathead screwdriver (2.0mm to 3.0mm blade width) or a plastic non-marring trim removal tool is ideal.
• Microfiber Cloth: Used to wrap the tip of the flathead screwdriver to prevent gouging, scratching, or chipping the soft ABS plastic of the key housing.
• Isopropyl Alcohol (90%+) and Cotton Swabs: Optional, but highly recommended for cleaning oxidized battery contacts inside the key fob.
• Anti-Static Workspace: A clean, dry, non-conductive surface (such as a wooden desk or silicone mat). Avoid working on carpeted areas to eliminate the risk of Electrostatic Discharge (ESD) damaging the PCB.
• Estimated Budget: $3.00 to $8.00 USD for a multi-pack of premium lithium batteries.
• Estimated Duration: 3 to 5 minutes per key fob.

Step-by-Step Guide to Disassembling and Replacing Your Subaru Key Battery

This operational guide covers the two most prevalent Subaru key fob designs: the modern rectangular/teardrop smart key (used for push-button start vehicles) and the older integrated teardrop key fob.

Procedure A: Modern Subaru Smart Key Fob (CR2032 Battery)

This method applies to smart fobs with proximity entry and push-button ignition, typically found on vehicles from 2015 to the present.

Step 1: Release the Mechanical Emergency Key

Locate the small, spring-loaded silver release button on the back of the key fob casing. Press and hold this button down with your thumb while simultaneously pulling the metal ring at the top of the fob. The mechanical emergency key will slide smoothly out of its internal sleeve. Set this key aside.

Step 2: Locate the Internal Pry Slot

Hold the key fob so the empty mechanical key sleeve is facing upward. Look inside the cavity. You will see a small, rectangular partition or notch molded directly into the plastic dividing wall between the outer seam. This is the designated pry point. Do not attempt to wedge your tool along the external side seams of the fob, as this will permanently deform the plastic housing and compromise its weather-resistant seal.

Step 3: Split the Key Fob Housing

Wrap the tip of your flathead screwdriver in a single layer of microfiber cloth to protect the plastic. Insert the wrapped tip directly into the internal pry slot. Gently, but firmly, twist the screwdriver like a key. You will hear a distinct "pop" as the internal retaining clips release and the two halves of the key fob begin to separate. Work your way slightly down the side seam with a plastic pry tool or your fingernail to fully split the front and back housings.

Warning: Do not force or pry with excessive upward leverage. A simple, controlled twisting motion of the screwdriver shaft is all that is required to separate the halves safely.

Step 4: Access and Remove the Circuit Board

Lay both halves of the key fob flat on your anti-static work surface with the interior components facing upward. In modern Subaru fobs, the green circuit board is housed inside a black, soft rubber dust-and-moisture boot. Carefully lift this rubber boot (which contains the PCB) out of the front half of the plastic shell.

Turn the rubber-wrapped PCB over to locate the battery compartment on the back. Gently peel back the flexible rubber lip to expose the silver CR2032 battery. Slide a non-conductive tool (such as a plastic toothpick or a small plastic spudger) under the edge of the battery to pop it out of its retaining clip.

Pro-Tip: Avoid using a metal screwdriver to pry the battery directly off the circuit board contacts. If you slip, you can scratch the delicate copper traces on the PCB or accidentally bridge a contact, causing a short circuit.

Step 5: Install the New CR2032 Battery

Take your new CR2032 battery out of its packaging. Ensure the positive terminal—marked clearly with a plus sign (+) and the battery model number—is facing upward (visible to you once installed). Slide the battery under the small gold-colored metal retaining tabs first, then press down firmly on the opposite side until the battery snaps securely into place.

Pro-Tip: Wipe the surface of the new battery with a dry microfiber cloth before installation. Skin oils from your fingers can transfer to the battery surface, leaving microscopic acidic deposits that increase electrical resistance and prematurely degrade battery life.

Step 6: Reassemble and Test the Key Fob

Align the rubber boot containing the PCB back into its molded seat inside the front plastic button cover. Ensure the rubber buttons line up perfectly with their respective cutouts. Place the back half of the plastic housing directly over the front half.

Press the two halves together firmly starting at the bottom and moving toward the top. You will hear a series of snaps as the perimeter clips lock. Slide the mechanical emergency key back into its slot until you hear it click. Stand near your vehicle and press the lock button to confirm successful operation.

Procedure B: Older Subaru Integrated Key Fob (CR1620 or CR1632 Battery)

This method applies to older Subaru models with physical ignition keys where the remote buttons are integrated directly into the key head.

Step 1: Open the Key Head Casing

Locate the small indentation seam along the side edge of the plastic key head, near where the metal key blade meets the plastic. Insert a small flathead screwdriver wrapped in microfiber into this notch. Twist the screwdriver gently to pop open the key head cover.

Step 2: Extract the Internal Transmitter Module

Inside the key head, you will find a small, sealed, independent plastic box (the transmitter module). Remove this module from the key shell.

Step 3: Open the Module and Swap the Battery

Using a precision flathead screwdriver, gently release the small latches securing the perimeter of the transmitter module box. Once opened, you will see the circuit board and the small coin-cell battery (typically a CR1620 or CR1632). Note the battery polarity (usually positive side facing down against the metal contacts, but verify your specific layout before removal). Remove the old battery, press the new one into place, snap the module box shut, place it back inside the key head, and press the outer key covers back together.

Subaru Key Fob Specifications and Battery Matrix by Model Year

The following table outlines the battery standards, mechanical key designs, and opening specifications for the most common Subaru models. Always verify the battery number engraved on your existing battery before purchasing a replacement.

Troubleshooting Post-Replacement Subaru Fob Failures

If your Subaru key fob does not function after installing a fresh battery, do not panic. These issues are almost always mechanical or physical rather than programming-related.

Issue 1: Key Fob Buttons Do Not Respond After Battery Replacement

• Root Cause: The new battery may be installed upside down (reversed polarity), or the positive and negative metal contact prongs on the circuit board have been bent flat, preventing them from touching the battery faces.
• Actionable Fix:
  1. Reopen the key fob.
  2. Verify that the positive (+) side of the battery faces upward (on modern smart keys) or is positioned according to the polarity markings in the tray.
  3. Inspect the gold-colored metal contact tabs inside the battery housing. If they look flattened, use a wooden toothpick or plastic tool to gently pry them upward by a fraction of a millimeter. This increases their spring tension and ensures a solid electrical connection with the battery.

Issue 2: Keyless Entry Works, But Dashboard Displays "Key Not Detected"

• Root Cause: The transmitter module is misaligned inside the plastic shell, or the battery is a low-quality brand-new cell that is outputting low voltage under load. Some cheap or counterfeit batteries sit slightly below 3.0 volts even directly out of the package.
• Actionable Fix:
  1. Open the fob housing and ensure the green circuit board and its protective rubber boot are completely seated flush in the front half of the plastic casing. If it is misaligned by even a millimeter, the buttons may not actuate the microswitches on the board.
  2. Test the voltage of your replacement battery using a digital multimeter. A fresh, healthy 3V lithium battery should read between 3.1V and 3.3V when unloaded. If it reads 2.9V or lower, discard it and buy a name-brand replacement (such as Panasonic, Energizer, or Duracell).

Issue 3: The Key Fob is Completely Dead and Will Not Respond After Trying Multiple Batteries

• Root Cause: The circuit board may have suffered Electrostatic Discharge (ESD) damage during handling, or the metal battery solder joints have cracked due to dropping the key fob.
• Actionable Fix:
  1. Inspect the circuit board under a magnifying glass for any signs of corrosion, liquid ingress, or cracked solder joints around the battery housing bracket.
  2. If the board is dirty or has suffered a liquid spill, clean it gently with a cotton swab dipped in 90%+ isopropyl alcohol and let it dry completely.
  3. If physical damage is present on the board, the key fob transmitter must be replaced and reprogrammed by an authorized Subaru dealership or an automotive locksmith equipped with a diagnostic programmer.

Frequently Asked Questions

Do I need to reprogram my Subaru key fob after changing the battery?

No, replacing the key fob battery does not delete the vehicle's transponder codes or remote keyless entry pairing. The transmitter memory is non-volatile, meaning it retains its programming even when the battery is completely disconnected.

Why is my Subaru dashboard still showing a "Key Battery Low" warning after replacement?

The vehicle's central computer registers low key battery status over multiple ignition cycles. After replacing the battery with a fresh, high-quality unit, you may need to drive your Subaru for 5 to 10 minutes, or start and turn off the vehicle three times, to allow the system to poll the key fob's updated voltage level and clear the dashboard warning automatically.

Can I start my Subaru if the key fob battery is completely dead?

Yes. If your smart key is completely dead, you can still start your vehicle. Hold the dead key fob directly up to the engine start button so that they are physically touching, and then depress the brake pedal. An internal Passive RFID transponder chip inside the key fob will draw power directly from the start button's magnetic field, allowing the engine to start even with no battery power in the key.

What is the difference between a CR2032 and a CR1632 battery for Subaru keys?

These two batteries differ significantly in physical size and capacity. The first two digits represent the battery diameter in millimeters (20mm vs. 16mm), and the last two digits represent the thickness in tenths of a millimeter (3.2mm vs. 3.2mm). They are not interchangeable. Always use the exact model number specified for your key housing.

Keep Your Subaru Running at Peak Performance

Ensuring your key fob battery is fresh prevents unexpected lockouts and guarantees seamless access to your vehicle. For more detailed maintenance tips or to purchase OEM Subaru replacement parts, consult your local certified Subaru dealership or trusted automotive specialist.