Are you experiencing issues with your BMW key fob? Specifically, is it failing to unlock or lock your doors remotely? If you own a slightly older BMW, particularly models around 2012 such as the X1 or 320d, you might be dealing with a common problem: a dead battery in a “Non-Comfort Access” key fob. Unlike some key fobs with easily replaceable batteries, these BMW fobs are sealed units with a rechargeable VL2020 battery that, while designed to last, can fail, especially if one of your fobs sits unused for extended periods. Replacing the entire key fob through BMW can be surprisingly expensive, often costing hundreds of dollars. However, there’s good news! You can fix your BMW key fob yourself with a bit of patience and some basic tools, saving a significant amount of money.
Many BMW owners are unaware that their “Non-Comfort Access” key fobs contain a rechargeable battery that isn’t designed to be replaced. Dealers sometimes fail to inform customers about the proper usage, which involves regularly using both key fobs to ensure they both receive charge from the car. These fobs charge wirelessly when inserted into the ignition slot while driving. If one fob is left in a drawer for a year or more, the battery can completely discharge and become unchargeable.
When this happens, you might find yourself quoted exorbitant prices for a replacement from BMW. While the key fob will still start the car when inserted into the slot (as this function doesn’t rely on the battery), the remote locking and unlocking functions will cease to work, forcing you to use the physical key – an inconvenience and a step back in modern car convenience.
Before resorting to costly replacements, consider this DIY solution to fix your BMW key fob. This guide will walk you through the process of opening your key fob and replacing the VL2020 rechargeable battery. It’s a delicate process, but definitely achievable for the average DIY enthusiast and a much more economical way to get your key fob working like new again.
Understanding Your BMW Key Fob Battery
BMW’s “Non-Comfort Access” key fobs, prevalent in models from around 2012, utilize a sealed, rechargeable VL2020 battery. This design differs from the “Comfort Access” fobs and many other car keys that use easily replaceable CR2032 batteries. The VL2020 battery is meant to recharge while the fob is used in the car’s ignition slot. However, if a fob is left unused for a long time, the battery can drain completely and fail to recharge, leading to a non-functional remote.
Symptoms of a Dead BMW Key Fob Battery
How do you know if your BMW key fob battery is the culprit? Here are the common signs:
- Remote locking/unlocking stops working: This is the primary symptom. The buttons on your fob will no longer lock or unlock the doors remotely.
- Key fob still starts the car: Inserting the key into the ignition allows you to start and drive the vehicle normally. This indicates the immobilizer chip is still working, but the battery for remote functions is dead.
- No response from any buttons: Regardless of which button you press, the car doesn’t respond (no flashing lights, no door locking/unlocking sounds).
If you experience these symptoms, especially if you know one of your key fobs has been sitting unused, a dead battery is highly likely.
DIY Fix: Step-by-Step BMW Key Fob Battery Replacement
Disclaimer: This repair involves opening a sealed electronic device and soldering. Proceed at your own risk. If you are uncomfortable with these steps, it’s best to seek professional help.
Here’s how to replace the battery and fix your BMW key fob:
Tools You’ll Need:
- Good quality, thin blade: A sharp knife or specialized tool for opening electronic devices.
- Small Phillips head screwdriver: To remove the PCB from the case (if necessary, depending on your fob model).
- Soldering iron and solder: For desoldering and resoldering the battery.
- Desoldering wick or pump (optional but helpful): To remove old solder.
- VL2020 battery with 90-degree pins: Ensure you get the correct battery type with the 90-degree pin orientation.
- CR2032 battery (for testing – optional): A standard CR2032 battery and some thin wires for a quick test.
- Fevibond or similar adhesive: To reseal the key fob case.
- Black enamel paint (optional): For touching up the edges of the case after opening.
- Multimeter (optional but recommended): To check battery voltage.
Step 1: Carefully Open the Key Fob
This is the most delicate part. The BMW key fob is tightly sealed.
- Insert the blade: Carefully insert the thin blade into the seam running around the key fob. Start at a corner and gently work your way around.
- Cutting, not prying: The goal is to cut through the adhesive seal, not to pry the case open. Apply gentle pressure and slowly move the blade along the seam. Be patient – this can take time.
- Separate the halves: Once you’ve gone around the entire seam, the key fob should split into two halves. Be very careful not to insert the blade too deep and damage the internal PCB.
Step 2: Access the PCB and Battery
- Gently open: Carefully separate the two halves of the key fob case.
- Expose the PCB: You should now see the internal Printed Circuit Board (PCB) with the VL2020 battery soldered onto it.
Step 3: Desolder the Old VL2020 Battery
- Identify solder points: Locate the two solder points where the VL2020 battery is connected to the PCB.
- Desolder carefully: Use your soldering iron to heat up each solder joint and carefully remove the old battery. A desoldering wick or pump can be helpful to remove excess solder. Be careful not to overheat the PCB or surrounding components.
Step 4: Test (Optional but Recommended)
Before soldering in the new battery, it’s wise to test if the battery replacement is indeed the solution.
- Prepare CR2032 test: Take a CR2032 battery and solder thin wires to its positive and negative terminals.
- Connect to PCB: Connect the wires to the solder points on the PCB where you removed the VL2020 battery. Ensure correct polarity (+ to + and – to -).
- Test the fob: Take the PCB with the temporary CR2032 connection to your car and test the buttons. If the car locks/unlocks, it confirms the battery was the issue.
Step 5: Solder in the New VL2020 Battery
- Position the new battery: Place the new VL2020 battery in the correct orientation on the PCB, aligning the pins with the solder points.
- Solder securely: Solder the battery pins to the PCB, ensuring a good, solid connection. Avoid cold solder joints.
Step 6: Reassemble the Key Fob
- Carefully place PCB back in case: Put the PCB back into one half of the key fob case.
- Apply adhesive: Apply a thin bead of Fevibond or similar adhesive around the edge of one half of the case.
- Join the halves: Carefully align and press the two halves of the key fob case together. Hold firmly until the adhesive sets.
- Touch up edges (optional): If the edges are rough after opening, use a small brush and black enamel paint to touch them up for a cleaner look.
Step 7: Test Your Repaired Key Fob
Once the adhesive is dry, test your fixed BMW key fob. The remote locking/unlocking should now be working perfectly!
Tips for Preventing BMW Key Fob Battery Issues
To prolong the life of your BMW key fob battery and avoid this issue in the future:
- Use both key fobs regularly: Alternate between your two key fobs every 3-4 months to ensure both get charged.
- Don’t leave a fob unused for long periods: Avoid leaving a key fob in a drawer for more than six months.
- Inform new BMW owners: If you sell your BMW, inform the new owner about the importance of using both key fobs to maintain battery health.
Conclusion
Fixing your BMW key fob by replacing the battery yourself is a cost-effective alternative to buying a new one from the dealer. While it requires some careful work, following these steps can save you a considerable amount of money and restore full functionality to your key fob. Remember to be patient, cautious, and enjoy the satisfaction of a successful DIY repair! If you found this guide helpful, share it with other BMW owners who might be facing the same problem.
