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What is the access key warning light on a Subaru?

The access key warning light on a Subaru signals an issue with the vehicle’s Keyless Access System, typically indicating that the key fob isn’t being detected or its battery is low. It can affect starting and remote access, and should be addressed promptly to avoid getting stranded.

What the Access Key warning light means

Subaru models equipped with Keyless Access and Push Button Start rely on a detection system that confirms the presence of a compatible key fob inside the vehicle or near the cabin. When the warning light comes on, it generally indicates a fault within that system, a weak key fob battery, or a failure in the receiver responsible for detecting the fob.

Common causes

The warning light commonly appears due to issues with the key fob, detection, or the system hardware. The following items cover the most frequent causes.

The key fob battery is dead or weak

The vehicle temporarily cannot detect the fob inside the cabin

A faulty Keyless Access System module or antenna

Immobilizer or software-related faults within the system

In many cases, the issue can be traced to a weak battery in the fob or a momentary detection glitch, but deeper hardware or software faults are possible and may require service.

How to troubleshoot at home

Before you head to a dealership, you can try a structured set of checks to identify and potentially resolve the issue.

These home troubleshooting steps focus on the most common fixes you can attempt before calling a dealer.

Replace the key fob battery: Use a fresh CR2032 coin cell, follow the fob’s case instructions to access the battery, and install with the correct orientation.

Test with a spare key fob: If the spare works normally, the primary fob is likely at fault and may need replacement or repair.

Try to start/unlock with the fob held close to the start button or door handles (as your model’s manual suggests): Some vehicles require the fob to be in direct proximity for detection.

Check for interference and placement: Keep the fob away from metal objects, RFID-blocking wallets, or other devices that can degrade the signal; ensure you’re inside the vehicle with the fob on your person.

If the light remains after these steps, or you still cannot start or unlock the vehicle, schedule service. A dealer can diagnose the Keyless Access System hardware and software with Subaru-specific tools.

When to seek professional help

If the warning light persists after home troubleshooting, or you experience repeated starting failures, door lock/unlock problems, or any alert related to the Keyless Access System, contact a Subaru dealer or a qualified mechanic promptly. Persistent warnings can indicate a degraded or failed key fob, a faulty receiver, or immobilizer faults that require professional diagnosis and repair.

Summary

The access key warning light signals a problem with Subaru’s Keyless Access System. The most common culprits are a dead or weak key fob battery, detection issues, or a hardware/software fault in the system. Start by replacing the fob battery, trying a spare fob, and ensuring proximity guidelines for your model. If the issue persists, seek professional service to diagnose the keyless module, antennas, and related electronics. Addressing the warning promptly helps maintain reliable access and starting capability.

How to change battery on Subaru Access Key?

To replace a Subaru access key battery, first remove the physical key by pressing the silver tab and pulling it out. Then, use the physical key or a small flathead screwdriver to gently pry open the key fob casing at the seam. Remove the old battery, replace it with a new CR2032 battery with the plus side facing up, reassemble the fob, and reinsert the physical key.

This video shows how to replace the battery in a Subaru key fob: 50sKey Fob RobYouTube · Aug 13, 2025
Step 1: Remove the physical key

Locate the silver release tab on the back of the key fob.
Press the tab and pull the physical key straight out.

Step 2: Open the key fob

Insert the tip of the physical key or a small, flathead screwdriver into the seam on the top of the fob where the key was.
Gently twist to pop the case open.

Step 3: Replace the battery

Locate the CR2032 battery inside. You may need to use a small screwdriver to gently pry the old battery out from its holder.
Insert the new CR2032 battery, making sure the plus (+) side is facing upwards.

Step 4: Reassemble the fob

Place the circuit board back into the fob, ensuring it is properly aligned.
Snap the two halves of the key fob case back together, making sure the seams are aligned.
Slide the physical key back into its slot until it locks into place.

You can watch this video to learn how to reassemble the key fob: 31sKey Fob RobYouTube · Aug 1, 2019

What does access key disabled mean on a Subaru?

An "access key disabled" message in a Subaru means the car can't communicate with the key fob, which can happen due to a weak or dead fob battery, a blown fuse, or a system synchronization error. To fix this, first check and replace the fob's battery, then try a system reset by touching the fob to the start button or performing a more thorough reset. If these steps don't work, a blown fuse or a more complex electronic issue may need professional diagnosis.
Common causes and solutions
1. Weak or dead key fob battery

Cause: The most common reason is a depleted battery in the key fob.
Solution: Replace the battery. If the problem happened immediately after replacing the battery, double-check that it was inserted correctly and in the right orientation.

2. Key fob and car synchronization error

Cause: After a battery change, the fob and the car's immobilizer system may lose synchronization.
Solution: Try the manual override method. With the fob in hand, hold it against the start button and press it while the brake pedal is depressed.

3. Blown fuse

Cause: The keyless entry system is protected by a fuse, which can blow, especially after electrical work or a short circuit.
Solution: Check your fuse box (often located near the battery or under the dashboard) for a blown fuse. If you find one, replace it with a new one of the exact same rating.

4. Other issues

Cause: Other potential issues include interference from other electronics, a faulty door lock actuator, or a problem with the Body Control Module (BCM).
Solution: Keep metallic objects away from the key fob and the start button. If the problem persists, you may need to have the vehicle diagnosed by a dealer to check for BCM errors or other electronic issues.

How to perform a system reset

Simple reset: Try pressing the lock and trunk buttons on the key fob simultaneously while near the car.
Full reset: Disconnect the car's battery for a few minutes, then reconnect it and try the system again.

If the issue persists after trying these steps, it's best to consult a professional service center for further diagnosis.

How to start a Subaru with a dead access key?

Button. Presto we're on the road again let's go. So put your key fob right up to the remote. You'll start it it doesn't even need to have a battery in it battery's right here.

What is the most serious Subaru warning light?

What is the most serious warning light? Of all Subaru dashboard symbols and meanings, the Oil Pressure Warning Light, Brake System Warning Light, and Battery Warning Light are possible causes for concern. Still, the Check Engine Warning Light is one of the most urgent symbols.

Kevin Bennett

Company Owner

Kevin Bennet is the founder and owner of Kevin's Autos, a leading automotive service provider in Australia. With a deep commitment to customer satisfaction and years of industry expertise, Kevin uses his blog to answer the most common questions posed by his customers. From maintenance tips to troubleshooting advice, Kevin's articles are designed to empower drivers with the knowledge they need to keep their vehicles running smoothly and safely.