Accidentally running your Mercedes key fob through the washing machine can be a heart-stopping moment for any car owner. The initial panic is understandable, especially when you consider the crucial role your key fob plays in accessing and operating your vehicle. But fear not! If you’ve found yourself in this exact predicament, you’re in the right place. This guide will walk you through how to safely open your Mercedes key fob to assess and potentially repair any water damage.
Before we begin, it’s critical to act fast. The first and most crucial step is to immediately remove the batteries. Do not press any buttons while the batteries are still inside, as this could lead to a short circuit and further damage the delicate electronics within.
Many Mercedes owners might assume a dunk in water means a costly trip to the dealership for a replacement key fob. However, with a bit of careful DIY, you might be able to salvage your existing key and save yourself significant expense. This article provides a step-by-step guide, inspired by community fixes, to open your Mercedes key fob, allowing you to clean and dry the internal components.
Tools You’ll Need
To successfully open your Mercedes key fob and address potential water damage, gather these readily available tools:
- Isopropyl Alcohol (50-70% concentration): This is essential for cleaning any oxidation or water residue on the electronic components. You can find this at most pharmacies or general stores.
- Cotton Swabs (Q-tips): You’ll need a plentiful supply for applying alcohol and gently cleaning delicate parts.
- Small Container: A shallow dish or container to hold isopropyl alcohol for dipping the electronic board.
- Flat Pliers: These will be your primary tool for carefully prying open the key fob casing.
- Thin, Flat Knife or Small Flathead Screwdriver: This will assist in separating glued components within the key fob.
Step-by-Step Guide to Opening Your Mercedes Key Fob
Let’s get started with the disassembly process. Follow these steps carefully to open your Mercedes key fob without causing further damage.
Step 1: Carefully Open the Key Fob Casing
The Mercedes key fob casing is typically held together by epoxy glue and plastic clips. The goal is to gently separate the two halves without breaking the plastic.
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Locate the Opening Point: Extend the mechanical key blade from the fob. This will reveal a small gap along the side of the key fob casing.
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Insert the Pliers: Position the tips of your flat pliers into this gap.
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Gently Pry Open: Apply gentle, steady pressure to pry the two halves of the fob apart. Work your way around the seam, moving in the direction indicated by the arrows in the image below. Be patient and avoid using excessive force, which could crack the plastic.
Caution: As you pry the case open, be mindful of the spring-loaded key mechanism. It’s a small part that can easily pop out and get lost. Try to keep the fob oriented in a way that prevents the spring from flying out.
Step 2: Remove the Electronic Board
Once the casing is open, you’ll see the internal components, including the electronic board.
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Carefully Extract the Board: Gently lift the electronic board out of the casing. You may be able to push from the battery compartment side to help dislodge it.
Important: Be extremely careful with the battery terminals. These are delicate and can be easily broken if mishandled. Avoid bending or applying excessive force to them.
Step 3: Detach the White Plastic Transponder Cover
The transponder, a crucial component for starting your car, is often covered by a small white plastic piece that is glued in place.
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Apply Isopropyl Alcohol: Use a cotton swab to apply a few drops of isopropyl alcohol around the edges of the white plastic cover. Let it sit for a minute to soften the adhesive.
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Pry Gently: Carefully insert your thin knife or flathead screwdriver between the transponder and the white plastic cover. Gently pry upwards to separate the cover from the transponder.
Caution: Apply pressure only to the plastic cover and avoid putting any force on the transponder itself. The transponder is a sensitive electronic component that you don’t want to damage.
Step 4: Remove the Transponder
Now that the plastic cover is removed, you can access the transponder. It is also typically glued to the casing.
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Apply Isopropyl Alcohol Again: Apply a few more drops of isopropyl alcohol around the transponder, where it is glued to the casing. Allow the alcohol to soak for a few minutes to loosen the adhesive.
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Carefully Pry Out the Transponder: Use your thin knife or flathead screwdriver to gently pry the transponder out. Insert the tool underneath the transponder and lift upwards.
Important: Note the orientation of the transponder as you remove it. You’ll need to reinsert it in the same direction during reassembly. Handle the transponder with utmost care to prevent damage.
Step 5: Clean Oxidized Contacts and Dry Components
With the key fob disassembled, you can now address any water damage and oxidation, especially if your key fob was washed.
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Inspect for Oxidation: Examine the electronic board for signs of oxidation, which often appears as white or greenish deposits on the metal contacts.
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Alcohol Bath: Pour a generous amount of isopropyl alcohol into your small 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 Cleaning: While the board is soaking, use a cotton swab dipped in isopropyl alcohol to gently rub all the contacts and areas affected by oxidation. After soaking, remove the board and repeat the cotton swab cleaning process.
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Drying Time: Allow all components, especially the electronic board, to air dry completely for at least 30 minutes. Ensure there is no moisture left before reassembling.
Step 6: Reassemble Your Mercedes Key Fob
Once everything is clean and dry, you can carefully reassemble your Mercedes key fob.
- Reinsert the Transponder: Place the transponder back into its position in the casing, ensuring it’s in the correct orientation as noted during disassembly.
- Place the Electronic Board: Carefully position the electronic board back into the casing, aligning it with the battery terminals and other components.
- Snap the Casing Back Together: Align the two halves of the key fob casing and gently press them together until they snap securely closed. You should hear a click as the plastic clips engage.
After reassembly, insert new batteries and test your Mercedes key fob. While this guide offers a potential DIY solution, there’s no guarantee of success, especially in cases of severe water damage. If your key fob still doesn’t function after cleaning and reassembly, it’s advisable to consult with a Mercedes-Benz dealership or a qualified automotive locksmith for professional assistance.
