Experiencing issues with your 2008 BMW key fob, especially in cold weather? A common culprit is a dead or dying key fob battery. Symptoms like inconsistent locking/unlocking or loss of personalized car settings can be frustrating. Before you rush to a dealership, you can easily tackle this yourself. This guide will walk you through replacing the battery in your 2008 BMW key fob, saving you time and money.
What You’ll Need for Your BMW Key Fob Battery Replacement
Before you begin, gather these essential items:
- Replacement Battery: You’ll need a VL2020 lithium-ion battery. Ensure you purchase the correct type with terminals in the right position. You can find these online at retailers like eBay.
- Sharp X-Acto Knife or Precision Blade: For carefully opening the sealed key fob casing.
- Non-Metallic Pry Tool: A credit card or plastic pry tool will work to gently lift the battery without damaging the circuit board.
- Soldering Iron and Solder: For desoldering the old battery and soldering in the new one.
Step-by-Step 2008 BMW Key Fob Battery Replacement Guide
Follow these steps to replace your 2008 BMW key fob battery:
Step 1: Purchase the Correct Replacement Battery
It’s crucial to get the right battery. For a 2008 BMW key fob, the VL2020 lithium-ion rechargeable battery is typically required. Pay close attention to the terminal placement on the new battery to match the old one before purchasing. Online marketplaces like eBay are good sources for these batteries.
Step 2: Carefully Open the Key Fob Casing
The BMW key fob is sealed and glued. Using a sharp X-Acto knife, carefully begin to cut along the seam of the fob. Work slowly and apply gentle pressure to avoid cutting too deep and damaging the internal circuit board (PCB). Take your time to separate the top and bottom halves of the key fob.
Step 3: Desolder the Old Battery from the PCB
Once open, you’ll see the PCB with the battery soldered in place. Use a non-metallic pry tool, like a credit card, to gently apply a small amount of pressure under the battery. Focus on the corner terminal first. Heat the corner solder joint with your soldering iron to desolder it. The corner terminal is easier to access first because the middle terminal has a longer lead.
Step 4: Solder the New VL2020 Battery into Place
Position the new VL2020 battery into the battery holes on the PCB. Hold the PCB by its edges and gently push the battery down into place. Apply heat to the middle battery terminal solder pad on the PCB, then to the corner terminal pad. The battery terminals should push through the existing solder and seat correctly. Ensure the battery is securely soldered to the PCB.
Step 5: Test and Reassemble Your BMW Key Fob
Before permanently sealing the key fob, dry fit the PCB back into the housing and test the key with your 2008 BMW. Check if the lock/unlock buttons and car start function work correctly. If everything is working, congratulations! You’ve successfully replaced your BMW key fob battery.
To reassemble, you have a couple of options. You can purchase a new key fob housing for a fresh look. Alternatively, you can simply glue the original housing back together. If you choose to glue it, use a gel-type cyanoacrylate glue sparingly to avoid it running and potentially gluing the PCB to the housing.
By following these steps, you can effectively replace the battery in your 2008 BMW key fob and resolve common key fob issues, especially those related to cold weather performance. This DIY approach is a cost-effective alternative to dealership replacements, getting you back on the road with a functional key fob.
