Discovering your Mercedes key fob has gone through the wash can be a moment of panic for any car owner. Modern key fobs are complex pieces of electronics, and exposure to water can lead to malfunctions. However, before you rush to replace your potentially expensive Mercedes key fob, there’s a DIY solution you can attempt at home. This guide will walk you through how to safely open your Mercedes key fob to clean and potentially repair it after water damage, focusing on addressing common issues like oxidation and short circuits.
Before we begin, it’s crucial to act fast if your key fob has been submerged in water. The longer water sits inside, the more damage it can cause. The first and most important step is to remove the batteries immediately. Do not press any buttons while the batteries are still inside a wet key fob, as this can cause further damage and potentially short-circuit the internal components.
This guide is designed to help you understand how to open a Mercedes key fob and perform a basic cleaning. While we aim to provide helpful information, please remember that this is a DIY approach, and keyfobx.com is not responsible for any damage you may cause to your key fob or vehicle. If you are uncomfortable with this process, it’s always best to consult a professional locksmith or Mercedes-Benz dealership.
Tools You’ll Need for Mercedes Key Fob Repair
To successfully open your Mercedes key fob and clean its internal components, gather the following tools:
- Isopropyl Alcohol (50-70%): This is essential for cleaning oxidation and displacing water. You can find this at most drugstores or pharmacies.
- Cotton Swabs (Q-tips): For precise cleaning of small components.
- Small, Shallow Container: To immerse the electronic board in isopropyl alcohol.
- Flat Pliers: To gently pry open the key fob casing.
- Small Flat Knife or Flat-head Screwdriver: To assist in opening the case and carefully separating components.
Step-by-Step Guide to Opening and Cleaning Your Mercedes Key Fob
Follow these steps carefully to open your Mercedes key fob and clean it after water exposure.
Step 1: Carefully Open the Key Fob Casing
The Mercedes key fob casing is typically held together by epoxy glue and plastic clips. To open the Mercedes key fob, start by extending the mechanical key blade. This will reveal a small gap in the casing.
- Insert Flat Pliers: Carefully insert the tips of your flat pliers into the small gap revealed when the key is extended.
- Gently Pry Open: Apply gentle pressure in the direction indicated by the arrows in the image below to begin separating the two halves of the fob. Work your way around the seam, gently prying it open. Be extremely cautious not to apply too much force, as you could damage the plastic casing.
- Control the Spring-Loaded Key: As you pry the case open, be mindful of the spring-loaded mechanism for the mechanical key. It can pop out unexpectedly. Keep a finger on it to prevent losing the small spring.
Step 2: Remove the Electronic Board and Transponder
Once you have successfully opened the Mercedes key fob casing, the next step is to carefully remove the internal electronic components.
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Remove the Electronic Board: Gently lift out the electronic circuit board. Be especially careful with the battery terminals. Avoid bending or breaking them. You can usually push from the battery compartment side to help ease it out.
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Detach the White Plastic Cover: Locate the white plastic cover that secures the transponder. It’s often glued to the transponder itself. Apply a couple of drops of isopropyl alcohol using a cotton swab to the edges of this plastic cover. Let the alcohol soak for a minute to soften the adhesive.
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Separate the Plastic Cover: Insert a small knife or flat screwdriver between the transponder and the white plastic holder. Gently pry to separate them. Important: Apply pressure to the plastic cover, not directly to the transponder, to avoid damaging it.
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Remove the Transponder: The transponder is also typically glued in place. Again, apply a few drops of isopropyl alcohol around the transponder and let it sit for a few minutes to loosen the adhesive.
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Carefully Pry Out Transponder: Using the small knife, gently pry the transponder from its housing. Exercise extreme caution not to damage the transponder itself. Note the orientation of the transponder before fully removing it, as it needs to be placed back in the same direction during reassembly.
With the transponder safely removed, you now have access to the electronic board for cleaning.
Step 3: Cleaning Oxidized Contacts on the Mercedes Key Fob
Water damage often leads to oxidation on the electronic contacts, which can prevent your key fob from working.
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Inspect for Oxidation: Examine the electronic board closely, especially the battery contacts and any other metallic parts. Oxidation will appear as a white or greenish buildup.
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Alcohol Bath: Pour a generous amount of isopropyl alcohol into your shallow container. Submerge the electronic board completely in the alcohol. Let it soak for 5-10 minutes. The alcohol will help displace water and dissolve oxidation.
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Gentle Scrubbing: After soaking, use a cotton swab dipped in isopropyl alcohol to gently scrub all contacts and areas affected by oxidation. Be patient and thorough.
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Drying Time: Once cleaned, allow all components to air dry completely for at least 30 minutes before reassembling. Ensure there is no residual moisture, as this could cause further problems.
Step 4: Reassembling Your Mercedes Key Fob
Once all parts are clean and dry, carefully reassemble your Mercedes key fob in reverse order of disassembly.
- Reinstall Transponder: Place the transponder back into its housing in the correct orientation (note the direction from when you removed it).
- Place Electronic Board: Carefully position the electronic board back into the key fob casing, ensuring the battery terminals align correctly.
- Close the Casing: Snap the two halves of the key fob casing back together. Press firmly until they are securely closed.
Conclusion
By following these steps, you can open your Mercedes key fob and attempt to repair it after water damage. Cleaning oxidized contacts with isopropyl alcohol can often restore functionality. However, if your key fob still doesn’t work after cleaning and reassembly, it may indicate more severe damage, and professional repair or replacement might be necessary.
Remember to always handle electronic components with care and to seek professional help if you are uncomfortable performing these steps yourself. Visit keyfobx.com for more guides and information on car key fob maintenance and repair.
