Is your Mercedes-Benz smart key fob failing to unlock your car doors reliably or struggling to start your engine? A common culprit is a dead or dying battery within your key fob. Fortunately, replacing the battery in your Mercedes smart key fob is a straightforward process you can easily accomplish at home without any special tools. This guide will walk you through each step, ensuring you can quickly restore full functionality to your key and get back on the road.
Before you begin, it’s important to identify the correct type of battery for your Mercedes smart key. While many models utilize CR2032 batteries, some, particularly older or specific series like the SLK with a three-button key, might require CR2025 batteries which are slightly slimmer. Consult your owner’s manual for definitive information, or carefully open your key fob to check the existing battery type before purchasing replacements. For this guide, we’ll focus on the more common two-button smart key which typically uses CR2032 batteries. You will need two new CR2032 batteries to complete this replacement.
Step-by-Step Mercedes Smart Key Battery Replacement Guide
Follow these simple steps to replace the battery in your Mercedes smart key fob:
Step 1: Locate the Seam and Remove the Key Blade
Examine your Mercedes smart key fob closely. You’ll notice a seam running around the top portion of the key, near where the metal key blade is housed. This seam indicates where the key fob casing can be opened.
First, you need to remove the metal key blade from the smart key. Locate the release lever, usually color-coded (often gray, black, white, or blue), situated near the base of the metal blade. Push this lever to release the blade and slide it out completely from the key fob. This metal key blade will also serve as the only tool you’ll need for the battery replacement process.
Step 2: Use the Key Blade to Open the Fob
With the metal key blade removed, you’ll use it to gently pry open the smart key fob casing. Look into the slot where you just removed the metal key blade. You will see a small gray plastic piece inside. This is the latch that secures the battery compartment.
Take the metal key blade and insert the “hook” portion – the end that normally sits inside the key fob – into the opening. Position the hook so it engages with the gray plastic latch inside the key fob housing.
Step 3: Access and Replace the Battery
While holding the smart key firmly in your hand, gently press the metal blade inwards, towards the direction of the arrow as shown in the image if available on your key. This action will push against the gray release latch. You should observe the latch moving slightly.
Maintain pressure on the metal blade to keep the latch depressed. Simultaneously, use your fingernail to gently pry upwards at the seam of the key fob, starting from the end where you inserted the blade. The internal battery compartment should now begin to slide out from the key fob casing.
Once the battery compartment is partially free, you can fully remove it from the key fob. You will now see the CR2032 batteries. Carefully slide out the old batteries one at a time, noting the polarity (+/-) orientation. Install the new CR2032 batteries, ensuring they are placed in the correct orientation.
Step 4: Reassemble the Key Fob
With the new batteries securely in place, slide the battery compartment back into the Mercedes smart key fob casing. Push it in until you feel and hear the latch click into place, confirming that it is securely closed.
Finally, slide the metal key blade back into its slot until it locks securely.
Conclusion
Congratulations! You have successfully replaced the battery in your Mercedes smart key fob. Test the key fob to ensure it is now working correctly, locking and unlocking your doors and starting your vehicle without issue. Regularly replacing your Mercedes smart key battery when you notice decreased range or responsiveness can prevent unexpected lockouts and ensure your key fob remains reliable. This simple maintenance task can save you time and potential frustration, keeping your Mercedes-Benz ownership experience smooth and convenient.
