How To Change the Battery in a Mercedes Key Fob

January 11th, 2025 by

Mercedes-benz key fob

If you’ve ever experienced issues with your Mercedes-Benz key fob, you know just how inconvenient it can be. The good news is that whether you’re dealing with a key fob that no longer unlocks your doors, starts your engine, or triggers the panic alarm, replacing your Mercedes key fob battery is often all you need to do. In this guide, our team at Mercedes-Benz of Birmingham, Alabama, will walk you through the process, from identifying your key fob type to changing the battery.

Identifying Your Mercedes Key Fob Type

The Mercedes key fob battery type and the number of batteries you’ll need depends on the specific key model of your car. There are two types of Mercedes key fobs: the newer Chrome SmartKey and the older SmartKey.

If you have a Chrome SmartKey, check the panic button to identify which version it is. Older Chrome SmartKeys have a circular panic button, while newer ones feature a triangular one. This is important because older Chrome SmartKeys need two batteries, while newer versions only need one. If you have an older Mercedes-Benz, you may have a durable plastic SmartKey instead of a Chrome SmartKey. This type of key fob requires two batteries regardless of the version.

Key batteries for Mercedes-Benz models are usually easy to source, especially if you go through your local dealership. While CR 2025 batteries are the most common, it’s always a good idea to verify your key fob type and order the correct battery size. If you have any questions about what type of battery to order for your Mercedes-Benz key fob, reach out to our parts department, and one of our experts can help.

Signs It’s Time To Change Your Key Fob Battery

If your Mercedes key stops working or you’re experiencing issues with its functionality, it’s time to replace the battery. However, there are other warning signs you can look out for to save you from unexpected inconvenience in the future. Here are some common signs your Mercedes key fob battery needs to be replaced:

  • Reduced range for locking/unlocking: If you need to stand closer to your vehicle than normal for the key fob to function, the battery may be losing power.
  • Delayed vehicle start: Difficulty starting your vehicle or needing multiple attempts could indicate a weak key fob battery.
  • Nonresponsive buttons: If the key fob no longer locks or unlocks doors or the panic alarm fails to activate, the battery may be the culprit.
  • Dashboard warning light: Some Mercedes-Benz models display a dashboard alert indicating your key fob battery is low. Pay attention to this notification to address the issue promptly.
  • Complete inoperability: If your key fob has stopped working entirely, the battery is most likely drained and needs immediate replacement.

Step-By-Step Guide for Replacing the Battery in Your Mercedes Key Fob

The good news is that replacing the battery in your Mercedes-Benz fob is easy, whether you have a Chrome SmartKey or a SmartKey. Once you’ve identified your key fob type, order the correct batteries and make sure you have a flathead screwdriver on hand. Then, simply follow these instructions to replace the battery in your Mercedes key fob and get it working like new again.

Replacing the Battery in a Chrome SmartKey

Here’s how to replace the battery in a Mercedes-Benz Chrome SmartKey fob:

  • Remove the emergency key: Pull the tab at the bottom of the fob to release the emergency key.
  • Open the key fob cover: Insert the narrow end of the emergency key or a flathead screwdriver into the slot and twist gently to pop off the cover.
  • Replace the battery: Remove the old battery and insert the new CR 2025 battery with the positive (+) side facing up.
  • Reassemble the fob: Snap the cover back into place and return the emergency key to its slot.

Replacing the Battery in a SmartKey

Here’s how to replace the battery in a Mercedes-Benz SmartKey fob:

  • Remove the emergency key: Pull the latch on the back of the fob to slide out the emergency key.
  • Access the battery compartment: Insert the emergency key or a flathead screwdriver horizontally into the slot and lift the battery compartment out.
  • Replace the batteries: Remove and replace the two old batteries with fresh CR 2025 batteries, ensuring the positive (+) sides face up.
  • Reassemble the fob: Reinsert the battery compartment and return the emergency key.

Key Fob Maintenance Tips and Best Practices

Here are a few extra tips and best practices to set you up for success next time you need to change the battery in your Mercedes key fob:

  • Avoid using sharp objects that could damage the key fob.
  • Always double-check that the batteries are inserted with the correct polarity.
  • Dispose of used batteries at an appropriate recycling facility.

Contact Mercedes-Benz of Birmingham With Your Auto Questions

If your Mercedes key isn’t working after you’ve followed all of the steps above, or you need assistance replacing your Mercedes key fob battery, we’re here to help. Send us a message or give us a call, and our expert technicians can answer your questions. Our parts department can also help you order replacement key fobs and batteries so you never have to worry about being locked out of your vehicle. Contact us today, order genuine Mercedes-Benz parts through us online, or schedule a service appointment to keep your car running at its best.

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