How to Replace the Battery in a Mercedes-Benz E320-4MATIC Key?

[StCarlos]

Method for replacing the battery in a Mercedes-Benz E320-4MATIC key: There is a button on the back of the key. Press this button and slide the back cover of the key forward to open it. The battery is located in a slot nearby. Remove the old battery after opening the slot and replace it with a new one. Then, reattach the back cover of the key and ensure it is properly installed. The Mercedes-Benz E320-4MATIC has a body length, width, and height of 5065mm, 1860mm, and 1482mm respectively, with a wheelbase of 3079mm. It is equipped with a 3.0T turbocharged engine, paired with a 9AT transmission, delivering a maximum power of 272 horsepower.

[PenelopeFitz]

I once replaced the battery for my friend's Mercedes-Benz E-class key, and it was actually quite simple. First, make sure the model is the E320-4MATIC, which uses a CR2025 coin battery. There's a small button on the side of the key—press it to eject the mechanical key. Use the metal blade as a tool to insert into the gap of the key casing and gently pry it open. Once the old battery is exposed, remove it with your fingernail or a plastic tweezer, being careful to note the positive and negative orientation. Insert the new battery with the shiny side facing up—if installed backward, it won't work. Align the cover and press it back into place, then test whether the lock button lights up with a red LED. The whole process takes about five minutes, but those with a heavy hand might break the clips, so I recommend watching a tutorial video for first-timers. Keep a spare battery (costing just a few bucks) in the car so you won’t panic if the key suddenly dies.

[Molly]

In our car enthusiasts group, we often discuss replacing key batteries. Mercedes key designs are quite similar. The E320 model's key is particularly easy to disassemble: First, locate the silver button on the side and press it to eject the metal key blade. Use the thin end of the key blade to gently pry along the seam of the casing until you hear a click, indicating the back cover has popped open. Be careful not to scratch the circuit board when removing the battery; it's best to use a plastic tool. The battery model is CR2025—don't get the wrong one, as it's available in supermarkets and convenience stores. When installing, place the battery with the gold contacts facing down, and listen for a crisp click to confirm it's properly seated. Before closing the cover, test the remote range—if it can unlock from 20-30 meters away, the battery is sufficiently charged. Doing it yourself is convenient and saves money, eliminating the need for a special trip to the dealership.

[DelReed]

Changing the battery is really easy—I just helped my neighbor with the same key model last week. You only need two things: a CR2025 battery and your phone's flashlight. Locate the small button at the bottom of the key, press it, and the metal key blade will pop out. That metal blade is the perfect tool to open the case—insert it into the seam, twist halfway, and the back cover will pop open. When removing the old battery, handle it gently as the circuit board is delicate. For the new battery, pay attention to the orientation—the side with text should face downward. Before snapping the cover back on, test the unlock button to check the indicator light—a red light means success. Keep three things in mind: don’t force the casing open, avoid touching the circuit board with your hands, and don’t let metal contact the battery. Once done, reinsert the mechanical key, and it’ll last another three to four years.

[OJesse]

As a seasoned Mercedes owner, here are some key reminders for you: First, go to the supermarket and buy a Panasonic or Sony CR2025 battery; off-brand ones don't last long. When opening the cover, be bold yet careful—insert the key blade into the shell gap, apply slight downward pressure, then lift upwards. You'll know it's right when you hear a 'pop' sound. After removing the battery, use a cotton swab to clean the contacts, as oxidation layers can form over time. When installing the new battery, always remember the '+' side faces up (the printed side), and align it with the marked slot. When closing the cover, press evenly on all four corners—avoid applying force on just one side. Finally, don't skip the testing step—repeatedly press the lock button to check the red light's brightness; if it's dim, it indicates poor contact. If you're really unsure, spend five bucks to have it replaced at a watch repair shop—they have professional tools.

[LaGabriel]

I've seen people break their keys trying to replace the battery, but the process is actually quite simple. Prepare a CR2025 coin-sized button battery, available at hardware stores for about three dollars. Press the metal button on the side of the key to release the mechanical key, but don't pull it out completely. Use the key blade as a lever by twisting it 30 degrees, and the casing will pop open easily. The old battery might be secured with a rubber ring—avoid forcing it out; gently push it out with a small flathead screwdriver instead. Pay attention to the battery orientation: Mercedes-Benz designs require the negative terminal to face upward during installation. After installing, first check the remote indicator light, then test the functionality by partially closing the cover. Only press it fully shut once everything works. Avoid water exposure and impacts during the process. If the key has keyless entry functionality, simply approach the car door and pull the handle after replacement to automatically activate it.