How To Change Subaru Key Battery: Step-by-Step Replacement Guide

Replacing a Subaru key fob battery takes less than five minutes and requires only a small flathead screwdriver and a standard lithium coin cell. Using the correct battery size—typically a CR2032 or CR1632 depending on your model year—ensures your integrated access system, keyless entry, and push-button start function reliably without triggering dashboard immobilizer warnings.

Pre-Operation & Equipment Checklist

Proper execution of a Subaru key fob battery replacement depends on having the correct equipment and understanding your specific key architecture. Modern Subaru key fobs generally fall into two categories: the traditional integrated mechanical-ignition key with a remote head, and the modern smart key fob used for push-button start systems. Before starting, verify your fob type to avoid damaging the plastic housing clips during disassembly.

• Essential gear, tools, and materials: A fresh lithium coin cell battery (CR2032 or CR1632), a precision flathead screwdriver or non-marring plastic pry tool, and a clean, lint-free workspace.
• Mandatory prerequisite knowledge and standards: Identify whether your fob features a physical emergency key release button or a hidden side-notch mechanism. Never touch the flat surfaces of the new lithium battery with bare skin; the natural oils from your fingers can cause premature self-discharge or corrosion.
• Estimated budget and duration benchmarks: Financial cost ranges between three and six dollars for a quality battery, while the entire procedural duration takes approximately three to five minutes.

Step-by-Step Fob Disassembly and Battery Replacement

Step 1: Extract the Mechanical Emergency Key

For modern Subaru push-button start fobs, locate the small sliding release tab or push-button on the top edge or back of the plastic casing. Slide or press this mechanism while simultaneously pulling outward on the metal emergency key blade. Once the mechanical key is completely removed, look inside the exposed slot to find a small auxiliary notch designed to fit the tip of your flathead screwdriver.

Pro-Tip: If your fob does not have an emergency key, look for a small seam running horizontally or vertically around the perimeter of the outer plastic shell.

Step 2: Separate the Key Fob Housing Halves

Insert the flathead screwdriver or a non-marring plastic pry tool into the designated slot or the outer perimeter seam. Gently twist the tool to pop the two plastic housing halves apart, working your way around the edges if necessary. Take care not to apply excessive torque, which can snap the internal plastic alignment pins or damage the waterproof rubber gasket lining the perimeter.

Step 3: Remove the Old Lithium Battery

Lift the internal circuit board or protective plastic cover if one is present to expose the coin cell battery housed within its metal or plastic retainer clip. Note the orientation of the battery, paying close attention to which side faces upward. Slide or gently pry the depleted battery out of its socket, ensuring you do not bend the delicate metal contact prongs that supply electrical current to the circuit board.

Step 4: Install the New Battery and Reassemble

Place the new lithium coin cell battery into the housing socket with the positive side facing upward, matching the orientation of the original battery. Snap the two plastic housing halves back together by applying firm, even pressure with your thumbs until all perimeter clips click securely into place. Reinsert the metal emergency key blade into its housing slot until the internal locking mechanism engages firmly.

Subaru Key Fob Battery Matrix and Technical Specifications

Common Site Failures and Field Fixes

• Root Cause: The red LED indicator on the key fob lights up when buttons are pressed, but the vehicle doors refuse to unlock.
  
  
  • Actionable Fix: The battery may be installed upside down. Open the fob housing and verify that the positive (+) side of the coin cell is facing outward or upward as designated by the markings on the circuit board retainer.
• Root Cause: The smart key fob still fails to communicate with the push-button start system after installing a brand-new battery.
  
  
  • Actionable Fix: Skin oils or manufacturing residue on the new battery can disrupt electrical continuity. Wipe both sides of the new coin cell with a clean microfiber cloth moistened with isopropyl alcohol before reinserting it into the fob.
• Root Cause: The plastic housing snaps or clips break during the separation process due to cold ambient temperatures.
  
  
  • Actionable Fix: Warm the key fob gently using a handheld hair dryer on a low setting for thirty seconds to make the injection-molded plastic more pliable prior to inserting your pry tool.

Frequently Asked Questions

What size battery does a Subaru key fob take?

Most modern Subaru push-button start smart keys utilize a CR2032 lithium coin cell battery. Older integrated ignition key fobs with remote buttons typically require a smaller CR1620 or CR2016 battery, so always inspect your specific casing before purchasing a replacement.

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

No, changing the battery in a Subaru key fob does not erase its programming or cryptographic pairing with your vehicle. The vehicle's internal computer retains the immobilizer and keyless entry codes permanently in non-volatile memory.

Why is my Subaru key fob still not working after a battery change?

If a new battery fails to restore functionality, verify that the battery contacts inside the fob are clean and making solid physical contact with the cell. In rare cases, physical damage to the internal circuit board or water intrusion may require a complete fob replacement.

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

For push-button start models, press your foot firmly on the brake pedal and hold the dead key fob directly against the engine start/stop button. The integrated transponder chip will communicate via near-field radio frequency to allow starting even with zero battery power.

How long does a Subaru key fob battery typically last?

A standard lithium coin cell battery in a Subaru key fob generally lasts between two and four years under normal operating conditions. Frequent use of remote engine start or keyless entry features can shorten this lifespan slightly.

Keep your Subaru operating seamlessly by checking your remote functions annually and replacing the battery at the first sign of reduced operating range.