Is your 2011 BMW 3 Series key fob acting up? Experiencing issues like reduced range, inconsistent locking/unlocking, or perhaps your BMW is not saving your personalized settings? A common culprit, especially in colder climates, is a weak or dead key fob battery. Fortunately, replacing the battery in your BMW 3 Series key fob is a straightforward DIY task that can save you time and money compared to visiting a dealership. This guide will walk you through the process step-by-step, ensuring you can get your key fob back to optimal working condition.
Before you begin, it’s important to understand why your key fob battery might be failing. BMW key fobs for the 2011 3 Series (E90 generation) use a rechargeable lithium-ion battery, specifically the VL2020 model. Over time, like all rechargeable batteries, these will degrade and hold less charge. Extreme temperatures, both hot and cold, can accelerate this degradation. When the battery weakens, you might notice the symptoms mentioned earlier.
What You’ll Need:
- Replacement Battery: Ensure you purchase the correct VL2020 battery. These are readily available online. Pay attention to the battery terminal orientation when ordering to match your original battery.
Locate VL2020 Battery Example - Sharp X-Acto Knife or Precision Blade: For carefully opening the key fob casing.
- Non-Metallic Pry Tool: A credit card or plastic trim tool works well to gently lift the battery.
- Soldering Iron and Solder: For desoldering the old battery and soldering in the new one.
- Safety Glasses: To protect your eyes during soldering.
- Optional: New key fob housing (if your current one is damaged or you desire a fresh look).
- Optional: Cyanoacrylate glue (gel type recommended) if reusing the original housing.
Step-by-Step Battery Replacement Guide:
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Carefully Open the Key Fob Casing: The BMW key fob is sealed with glue, requiring a careful approach to open it without damaging the internal components. Using your sharp X-Acto knife, gently score along the seam of the key fob casing. Work slowly and patiently, making multiple shallow passes rather than trying to cut through in one go. Avoid cutting too deep to prevent damage to the circuit board (PCB) inside.
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Desolder the Old Battery: Once the casing is open, you’ll see the PCB with the battery soldered in place. To remove the old battery, you’ll need to desolder it. Using a non-metallic pry tool like a credit card, gently apply a small amount of upward pressure to the battery. Then, apply heat to one of the battery terminals with your soldering iron to melt the solder. Start with the corner terminal, as it’s more accessible. The terminal closer to the battery’s center has a longer lead and is easier to access once the corner is free. Be careful not to apply excessive heat to avoid damaging the PCB.
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Solder in the New Battery: Place the new VL2020 battery into the battery holes on the PCB, ensuring correct polarity and terminal alignment. Hold the PCB by its edges and gently push the battery down into place. Apply heat to the battery terminals from the solder side of the PCB. The heat will melt the existing solder, and the battery terminals will slide into position. Solder both terminals securely, ensuring good electrical contact.
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Test and Reassemble: Before permanently sealing the key fob, dry-fit the PCB back into the housing and test the key fob functions on your 2011 BMW 3 Series. Check if the locking/unlocking works correctly and if your car now remembers your personalized settings. If everything is working as expected, proceed to reassembly.
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Seal the Key Fob: You have a couple of options for resealing your key fob. You can purchase a new replacement housing for a factory-fresh look. Alternatively, if you are satisfied with your current housing, you can carefully glue it back together. If gluing, use a gel-type cyanoacrylate glue sparingly to avoid it running and potentially gluing the PCB to the housing. Apply a small amount along the seam and press the two halves of the casing together until the glue sets.
Conclusion:
Replacing the 2011 Bmw 3 Series Key Fob Battery is a cost-effective DIY solution to common key fob issues. By following these steps and taking your time, you can restore your key fob to full functionality and avoid unnecessary dealership costs. Remember to use the correct VL2020 battery and exercise caution when opening and soldering the key fob components. With a little patience, you can successfully complete this repair and enjoy the convenience of a fully functional BMW key fob once again.
