Experiencing issues with your 2009 BMW 328i key fob, especially in cold weather? It’s a common problem where the key fob becomes unresponsive, failing to lock or unlock your doors remotely. You might also notice your car losing personalized settings like radio presets after starting. This often points to a low battery in your key fob. Fortunately, replacing the battery yourself is a straightforward process. This guide will walk you through replacing the battery in your 2009 BMW 328i key fob, saving you time and money.
Before you begin, ensure you have the correct replacement battery. The 2009 BMW 328i key fob typically uses a VL2020 Lithium-Ion battery. You can purchase these online from retailers like eBay or Amazon.
Refer to this link for the correct battery type to confirm you are getting the right one. Pay close attention to the battery terminal orientation when purchasing, as it needs to match your original battery.
Tools Needed:
- New VL2020 Battery
- Sharp X-Acto knife or similar precision knife
- Non-metallic pry tool (credit card or plastic spudger)
- Soldering iron and solder
Step-by-Step Battery Replacement:
Step 1: Carefully Open the Key Fob
The BMW key fob is sealed with glue, requiring careful opening. Using a sharp X-Acto knife, gently score along the seam of the key fob casing. Work slowly and avoid cutting too deep to prevent damage to the internal circuit board (PCB). Patience is key here.
Step 2: Desolder the Old Battery
Once opened, you’ll see the PCB and the battery. Use a non-metallic pry tool, like a credit card, to gently apply pressure under the battery corner to create a small gap. Then, using your soldering iron, desolder the corner terminal of the battery first. This is crucial because the other terminal has a longer lead, making it harder to access initially.
Step 3: Solder in the New Battery
Place the new VL2020 battery into the designated holes on the PCB, ensuring correct polarity. Hold the PCB by its edges and apply slight downward pressure on the battery to ensure good contact. 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 seat properly.
Step 4: Test and Reassemble
Before permanently sealing the key fob, dry fit the PCB back into the housing and test its functionality. Check if the key fob locks/unlocks the car and if your personalized settings are restored when you start the engine. If everything works as expected, proceed to reassembly.
Step 5: Glue the Key Fob Shut
You have two options for reassembling your key fob: purchase a new replacement housing or simply glue the original one back together. If you choose to glue it, use a gel-type cyanoacrylate glue sparingly. Apply it to the edges of the casing and carefully press the two halves together. Gel glue prevents running and minimizes the risk of accidentally gluing the PCB to the housing.
Congratulations! You have successfully replaced the battery in your 2009 BMW 328i key fob. This simple DIY task can restore your key fob’s functionality and prevent further inconvenience, especially during cold weather conditions. Remember to dispose of the old battery responsibly.
Disclaimer: This guide is for informational purposes only. Proceed at your own risk. We are not responsible for any damage caused by following these instructions.
