How to Change the Battery in a Mercedes Key Fob

If you’ve ever pressed the button on your Mercedes key fob only to find it won’t unlock the door, it might be time to replace the battery. It’s an easy process you can do right at home. Our team at Mercedes-Benz of Tyler has put together this quick guide to help you through the process of changing the battery.

Quick Signs Your Mercedes Key Fob Battery Is Dying

Some signs that it’s time for a battery change in your Mercedes key fob include:

Smaller Operation Range

One sign your Mercedes key battery is getting low is reduced range. If it’s less responsive when you try to use it from inside the house, but will still work when you’re close to the car, it’s a sign that the battery is not as strong anymore.

Unresponsive Buttons

A failing battery can cause some buttons on the key fob to become unresponsive. If certain buttons don’t function correctly or require a little extra force to respond, a new battery is likely needed.

Inconsistent Functionality

As the battery ages, it can cause the fob to work inconsistently. Sporadic function shouldn’t be ignored. It could lead to a situation where you are locked out of your Mercedes.

Warning Light

Some Mercedes-Benz models will display a warning light on the dashboard when the vehicle senses a low battery. It could display “Key Battery Low” or provide a reminder to “Replace Key Battery.” Most Mercedes key batteries will last about two or three years, depending on their usage.

Step-by-Step Guide: How to Change Your Mercedes Key Fob Battery

Once you’ve determined that your key fob needs a battery change, you can easily do so on your own. Mercedes-Benz vehicles have two types of keys: the Chrome Key and the Smart Key. The Smart Key has a plastic casing and is used with older model vehicles. Chrome keys come with the newer Mercedes-Benz models and have a metal casing and a sleeker, more modern design.

There are two versions of the Chrome Key. You can tell what version you have by looking at the panic button. The older Chrome keys have a circle, which needs just one battery. The newer version has a triangle button and may need two batteries.

Changing a Chrome Key Fob

1. Open the chrome key by pulling down on the silver tab at the bottom of the key. Press the button until it releases, and then slide the mechanical key out.
2. Use the mechanical key to unlock the battery compartment by pushing the key onto the flat end of the fob. This will open the key cover.
3. Remove the old battery or batteries using a screwdriver or fingernail, making note of the battery orientation.
4. Insert the new battery the same way the old one came out, pressing gently to secure it in place
5. Put the battery cover back on
6. Insert the mechanical key back into its slot

Changing a Smart Key Fob

1. Press the release button to access the mechanical key
2. Press the mechanical key into the slot at the end of the key fob to open the battery compartment
3. Remove the old battery, making note of the orientation
4. Insert the new battery, ensuring it is properly oriented. Press it gently to secure it in place
5. Put the battery cover back on
6. Insert the mechanical key back into its slot

Battery Types and Specifications for Different Mercedes Models

All Mercedes key fobs use coin-style batteries that are widely available at department and electronics stores. The battery size for a Mercedes key fob varies depending on the specific model and model year.

Newer models with the Chrome Key typically use one CR2025 or CR2032 battery. The older Smart Key fobs typically require two CR2025 batteries. The best way to determine what you need is to open the battery compartment and look at the current battery.

Programming and Syncing Your Key Fob After Battery Change

In many cases, just replacing the battery in the fob will get it working again. But if it doesn’t, there is probably a simple solution. The first step is to re-sync your key fob. In some older Mercedes-Benz models, removing the battery can cause the fob to lose its synchronization with the car.

The re-syncing process is simple. Start by placing the key in the ignition and turning it to the “ON” position. Press and release the “Lock” button on the key fob while it is still in the ignition, then press and hold the “Unlock” button. While you still have the “Unlock” button pressed, quickly press the “Lock” button five times. Release both buttons and wait for a few seconds. Finalize the syncing process by pressing “Lock” or “Unlock” one more time.

This process should work for most 2015 Mercedes-Benz models or older, but newer models have a more advanced security feature that may require specialized equipment to complete the re-syncing process. This feature is in place to ensure that only authorized keys can be synced with your vehicle to prevent theft. If you have one of these newer models, you may need to bring it to the experts at Mercedes-Benz of Tyler for assistance.

Schedule A Service Appointment

If you’ve replaced the battery and tried the re-syncing process, but the key still does not work, it may be time to call in the professionals.

Some signs that you may need to call a professional include:

• No response from the key fob
• A “Key Not Detected” indicator light on the dashboard
• Visible damage to the key fob

Contact us at Mercedes-Benz of Tyler for a service appointment, and we will get your key fob up and running again.

We Can Help With All Your Mercedes-Benz Key Fob Questions

Do you have more questions about replacing the battery in your key fob, or need some help getting it to work again? Contact us at Mercedes-Benz of Tyler. Our highly trained service technicians know what to look for and can troubleshoot any issues. Visit us at 3274 Professional Dr., Tyler, TX 75701, or give us a call at 903-534-7060.