Is your 2007 BMW 328i key fob acting up, especially when the temperature drops? You might be experiencing the frustration of a key fob that struggles to lock or unlock your car in the cold. Perhaps you’ve also noticed your personalized settings, like radio presets, disappearing after starting your vehicle. These are common signs of a low battery in your BMW 328i key fob. Before you rush to the dealership, consider this cost-effective and straightforward DIY solution: replacing the key fob battery yourself.
This guide will walk you through replacing the battery in your 2007 BMW 328i key fob. It’s a task you can accomplish at home with a few simple tools and a replacement battery. While some online resources might show less ideal methods, we’ll focus on a safe and effective approach to get your key fob working like new again.
What You’ll Need for a 2007 BMW 328i Key Fob Battery Replacement
Before starting, gather these essential items:
- Replacement Battery: You’ll need a VL2020 Lithium-Ion battery. Ensure the terminals are correctly oriented (approximately 90 degrees offset) for proper installation. You can find these batteries online from retailers like eBay.
- Sharp X-Acto Knife or Precision Blade: For carefully opening the glued key fob casing.
- Non-Metallic Pry Tool: A credit card or plastic pry tool will help gently lift the battery without damaging the circuit board.
- Soldering Iron and Solder: To desolder the old battery and solder in the new one.
Step-by-Step Guide to Replacing Your BMW Key Fob Battery
Follow these steps to replace your 2007 Bmw 328i Key Fob Battery:
Step 1: Carefully Open the Key Fob Casing
The BMW key fob is sealed with glue, so you’ll need to carefully cut it open. Using your sharp X-Acto knife, slowly and patiently cut along the seam of the key fob. Important: Avoid cutting too deep, as you risk damaging the internal circuit board (PCB). Take your time and work your way around the entire perimeter of the fob.
Step 2: Desolder the Old Battery
Once the fob is open, you’ll see the circuit board and the battery. Take your non-metallic pry tool (like a credit card) and gently apply a small amount of pressure under the battery to create slight tension. Then, using your soldering iron, carefully desolder the corner terminal of the battery. It’s recommended to start with the corner terminal because the middle terminal’s lead is longer and harder to access initially.
Step 3: Solder in the New Battery
Place the new VL2020 battery into the designated holes on the circuit board. Hold the PCB by its edges and gently press down on the new battery to ensure the terminals align with the solder points. Apply heat with your soldering iron to the middle terminal first, then the corner terminal. The battery terminals should push through the existing solder and securely seat into place.
Testing and Reassembling Your Key Fob
Step 4: Test the Key Fob
Before permanently sealing the key fob, dry fit the PCB back into the housing and test its functionality. Check if the lock and unlock buttons work and if your BMW recognizes your personalized settings after starting the car. If everything works correctly, proceed to the final step.
Step 5: Reassemble the Key Fob
You have two options for reassembling your key fob:
- Replace the Housing: For a more professional finish, you can purchase a new key fob housing. This will give your key fob a fresh, undamaged look.
- Glue the Original Housing: If you prefer a budget-friendly approach, you can simply glue the original housing back together. Use a gel-type cyanoacrylate glue sparingly to avoid it running and potentially gluing the PCB to the housing. Apply a thin bead of glue along the seam and carefully press the two halves of the fob together until the glue sets.
Congratulations! You’ve successfully replaced the battery in your 2007 BMW 328i key fob. By following these steps, you can restore your key fob’s functionality and avoid unnecessary trips to the mechanic or dealership. Enjoy the convenience of a fully working key fob, even in cold weather.
