Accidentally running your Mercedes-Benz key fob through the washing machine can be a moment of panic for any car owner. Discovering your key fob soaked and potentially damaged can feel like a costly mishap. But before you rush to the dealership for an expensive replacement, take a deep breath! Often, a waterlogged key fob can be salvaged with a bit of careful DIY and some household items. This guide will walk you through the process of safely opening your Mercedes key fob, allowing you to assess the damage and potentially fix it yourself.
First and foremost, do not press any buttons on your wet key fob. The immediate crucial step is to prevent further damage by removing the batteries as quickly as possible. Attempting to use the key fob while it’s wet can lead to short circuits and more serious electronic damage.
This guide is inspired by a resourceful fix shared in the car enthusiast community and adapted specifically for Mercedes-Benz key fobs. We’ll show you how to disassemble your key fob to clean and dry the internal components, potentially saving you from a costly replacement.
Here’s what you’ll need to get started:
- Isopropyl Alcohol (50-70%): This common household item, often found in first-aid kits or pharmacies, is essential for cleaning electronic components and displacing water.
- Cotton Swabs (Q-tips): You’ll need plenty of these for gentle cleaning and application of isopropyl alcohol.
- Small Container: A shallow dish or container is needed to submerge the electronic circuit board in isopropyl alcohol.
- Flat Pliers: These will help you gently pry open the key fob casing without causing damage.
- Small Flat Knife or Flathead Screwdriver: A thin, flat tool is necessary to carefully separate glued components within the key fob.
Step-by-Step Guide to Opening Your Mercedes Key Fob
Now, let’s get started with the disassembly process. Follow these steps carefully to open your Mercedes key fob:
Step 1: Begin Prying Open the Casing
Locate the small gap that appears when you extend the metal key blade from the fob. This gap is your starting point. Take your flat pliers and carefully insert the tips into this gap.
Step 2: Gently Separate the Front Half
Apply gentle pressure with the pliers in the direction indicated by the arrows in the image. The goal is to gradually pry open the front half of the key fob casing. Work your way around the seam, gently pushing and separating the two halves. Be extremely cautious during this step to avoid letting the spring-loaded key blade mechanism pop out unexpectedly. Losing this small spring can be a major setback in reassembling your key fob.
Step 3: Remove the Electronic Circuit Board
Once the case is open, you’ll see the internal electronic components. Carefully remove the electronic circuit board from the casing. Pay close attention to the battery terminals during this step. These terminals are delicate and can be easily broken if mishandled. Gently push from the battery compartment side to ease the board out.
Step 4: Detach the Plastic Cover and Transponder
The transponder, a small but crucial component, is often covered by a white plastic holder and secured with adhesive. To remove this, apply a few drops of isopropyl alcohol to a cotton swab and gently dab it around the edges of the white plastic cover. Let the alcohol soak for a minute to loosen the adhesive.
Next, carefully insert a small, flat knife or screwdriver between the transponder and the white plastic holder. Gently pry to separate the plastic cover. Exercise extreme caution not to apply pressure directly to the transponder itself, as it is fragile and essential for your key to communicate with your car.
Similarly, the transponder itself is likely glued to the casing. Repeat the process of applying isopropyl alcohol around the transponder and letting it soak briefly. Then, gently use the small knife to pry the transponder loose. Remember the orientation of the transponder as you remove it, as it will need to be placed back in the same direction during reassembly.
Step 5: Cleaning and Drying the Components
Now that you have successfully opened your Mercedes key fob, you can inspect the internal components for water damage or oxidation, especially if your key fob was washed. If you see signs of oxidation (a white or greenish buildup), this is where the isopropyl alcohol comes in handy.
Pour a generous amount of isopropyl alcohol into your small container and fully submerge the electronic circuit board. Let it soak for 5-10 minutes. The alcohol will help to displace any water and dissolve oxidation. While soaking, you can use a cotton swab dipped in alcohol to gently clean the contacts and other areas of the circuit board. After soaking, remove the board and use dry cotton swabs to thoroughly dry all components. Allow everything to air dry for at least 30 minutes to ensure all moisture evaporates before reassembly.
While waiting for the components to dry, take the opportunity to clean the inside of the key fob casing with isopropyl alcohol and cotton swabs as well to remove any dirt or residue.
Reassembling Your Key Fob
Once all parts are completely dry, carefully reassemble your Mercedes key fob in the reverse order of disassembly. Ensure the transponder is placed back in its original orientation. Snap the two halves of the key fob casing back together until they are securely closed.
After reassembly, insert new batteries and test your key fob. In many cases, cleaning and drying the components is enough to restore functionality. However, if your key fob still doesn’t work, there may be more serious damage, and professional repair or replacement might be necessary.
This DIY guide provides a practical first step in attempting to fix your Mercedes key fob after it has been exposed to water. By carefully following these steps, you can potentially save yourself time and money.
