Is your 2008 BMW key fob acting up, especially when the temperature drops? You’re not alone. Many BMW owners experience issues with their key fobs in cold weather, from failing to lock or unlock doors to losing personalized car settings. This often points to a common culprit: a weak key fob battery. Instead of rushing to the dealership and spending a hefty sum, you can easily replace the battery yourself. This guide will walk you through each step to replace your 2008 Bmw Key Fob Battery, saving you time and money.
Replacing the battery in your 2008 BMW key fob is a straightforward DIY task. Here’s how to do it:
- Purchase the Correct Battery
The first and most crucial step is to get the right battery. For most 2008 BMW key fobs, you’ll need a VL2020 lithium-ion battery. It’s important to note the orientation of the terminals on your old battery before ordering, as they are typically offset at a 90-degree angle. You can easily find these batteries online. A reliable source like eBay is a good place to start:
New VL2020 Battery for BMW Key Fob (eBay)
- Carefully Open the Key Fob
BMW key fobs are designed to be sealed, meaning they are glued shut. To access the battery, you’ll need to carefully cut open the fob. This requires patience and a sharp X-acto knife. Take your time and gently score along the seam of the key fob. Crucially, avoid cutting too deep to prevent damage to the internal circuit board (PCB). Work your way around the entire seam, gradually deepening the cut until you can pry the fob open.
- Desolder the Old Battery
Once the fob is open, you’ll see the PCB with the battery soldered in place. To remove the old battery, you’ll need a soldering iron and a non-metallic pry tool. A credit card or a plastic spudger works well as a non-metallic pry tool.
Apply a small amount of tension to the battery using your pry tool. Focus on the corner terminal first, as it’s easier to access. Heat the solder joint of the corner terminal with your soldering iron until the solder melts. Once molten, gently lift the terminal with your pry tool. Repeat this process for the other terminal. Starting with the corner terminal is recommended because the middle terminal often has a longer lead, making it harder to get under and apply tension initially.
- Solder in the New Battery
Now it’s time to install the new VL2020 battery. Place the new battery into the designated holes on the PCB. Hold the PCB by its edges and gently push the battery down into place. Apply heat to the middle terminal first, then the corner terminal, allowing the battery terminals to push through the existing solder and seat properly. Ensure the battery is flush against the PCB and securely soldered.
- Test the Key Fob
Before permanently closing the key fob, it’s crucial to test if the new battery works. Dry fit the PCB back into the housing and test all the key fob functions – locking, unlocking, and starting your 2008 BMW. If everything works as expected, congratulations! You’ve successfully replaced your BMW key fob battery.
- Reassemble the Key Fob
For the final step, you have a couple of options to reassemble your key fob. You can purchase a new replacement housing for a fresh look. Alternatively, if you’re not concerned about aesthetics, you can simply glue the original housing back together. If you choose to glue it, use a gel-type cyanoacrylate glue sparingly. Gel glue is less likely to run and get into unwanted areas. Apply a thin bead of glue along the seam and carefully press the two halves of the key fob together. Avoid using excessive glue to prevent accidentally gluing the PCB to the housing.
By following these steps, you can easily replace your 2008 BMW key fob battery and resolve common cold weather issues and restore your personalized settings. This DIY repair is a cost-effective alternative to dealership service and empowers you to maintain your BMW yourself.
