DIY Guide: Replacing Your 2001 BMW Key Fob Battery

Is your 2001 BMW key fob starting to act up? Are you finding yourself pressing the buttons multiple times, or needing to be right next to your car for it to respond? These are classic signs that your 2001 Bmw Key Fob Battery is dying and needs replacing. Forget urban legends about batteries recharging from the car – it’s simply not true for this model. The good news is, replacing the battery in your BMW key fob is a straightforward DIY task that can save you a trip to the dealership and unnecessary expense. This guide will walk you through each step to successfully replace your 2001 BMW key fob battery and get your remote working like new again.

Recognizing the Signs of a Dying Key Fob Battery

Before you dive into the replacement process, it’s important to confirm that a low battery is indeed the issue. Common symptoms of a failing 2001 BMW key fob battery include:

• Reduced Range: You need to be much closer to your BMW for the key fob to lock or unlock the doors.
• Intermittent Operation: Buttons become less responsive, requiring multiple presses to activate functions.
• Complete Failure: The key fob stops working altogether, even when you are right next to the vehicle.
• Inconsistent Locking/Unlocking: Sometimes the fob works, sometimes it doesn’t, indicating an unreliable power source.

If you are experiencing these issues with your 2001 BMW key fob, replacing the battery is the first and most likely solution.

Gathering Your Tools and Materials

To replace your 2001 BMW key fob battery, you’ll need to gather a few tools and the correct replacement battery. Here’s what you’ll need:

• Replacement Battery: The 2001 BMW key fob battery is a Panasonic VL2020 with custom leads. You can search online for “Panasonic VL2020 with leads” to find a supplier. While versions with pre-attached leads are available, a plain VL2020 battery can also be used with careful soldering.
• Vice-Grip: To securely hold the key while opening the fob.
• Paint Scraper: For initial prying and separating the glued fob casing.
• Sharp Knife: A utility knife or similar for carefully slicing along the seam of the fob.
• Small Tipped Soldering Iron: For desoldering the old battery and soldering in the new one.
• Silver Solder: For making reliable electrical connections.
• Small Chisel or Pocketknife: To help remove the old battery leads from the battery.
• Wide Jaw Pliers (Channel-Locks): To hold the circuit board steady during soldering.
• Rubber Band: To apply gentle pressure to the pliers holding the circuit board.
• Plastic Glue: For re-sealing the key fob casing.
• Clamps or Rubber Bands: To hold the fob halves together while the glue dries.

Step-by-Step Battery Replacement Guide

Now, let’s get to the battery replacement process for your 2001 BMW key fob.

Step 1: Opening the Key Fob Casing

The 2001 BMW key fob is notoriously glued shut, requiring some careful effort to open.

1. Secure the Key: Hold the metal key part of the fob firmly with the vice-grip. This provides leverage and stability.
2. Start Prying: Begin at the key ring end of the fob. Insert the paint scraper into the seam where the two halves of the plastic casing meet.
3. Slice and Pry: Carefully use the sharp knife to slice along the seam of the fob casing. Combine slicing with gentle prying using the knife or scraper to gradually crack open the glued case. Work your way around the perimeter of the fob, taking your time to avoid damaging the plastic.

Step 2: Identifying and Removing the Old Battery

Once the fob is open, you’ll see the internal components.

1. Locate the Battery: The 2001 BMW key fob battery (VL2020) sits in a designated well within the key fob casing, on the opposite side of the PCB (Printed Circuit Board) from the micro switches.
2. Observe Lead Connections: Note the positive and negative leads of the battery are soldered to the PCB. The negative lead is typically on the upper left, and the positive on the upper right. The leads are often keyed with different sizes where they go through the board.
3. Prepare for Desoldering: Use the wide jaw pliers to grip the PCB. Apply a rubber band to the pliers’ handles to maintain a gentle, consistent pressure – avoid squeezing too tightly as you could damage the board.
4. Desolder the Old Battery: Apply the hot soldering iron to the back of each battery lead on the PCB. Wait for the solder to melt, then gently pull the lead free from the board. Repeat for both leads to remove the old battery.
5. Remove Custom Leads (If Necessary): If you are using a plain VL2020 battery without pre-attached leads, use the chisel or pocketknife to carefully pry the custom leads off the old battery. You will reuse these leads.

Step 3: Soldering the New Battery

Now it’s time to install the new 2001 BMW key fob battery.

1. Solder Negative Lead: Solder the negative lead (the smaller through-pin lead) to the bottom (non-writing side) of the new VL2020 battery. Use a small amount of solder to ensure a good connection.
2. Resolder Negative Lead to PCB: Resolder the negative lead back into its original position on the PCB. Double-check the orientation, ensuring it matches the original battery placement. The battery should sit in the center of the white insulating pad on the PCB.
3. Solder Positive Lead: Solder the positive lead (the larger through-pin lead) to the top of the new battery and then resolder it to its corresponding position on the PCB. Again, use a minimal amount of solder and ensure correct orientation.

Step 4: Reassembling the Key Fob

With the new 2001 BMW key fob battery soldered in place, it’s time to reassemble the fob.

1. Clean Fob Edges: Clean up any frayed plastic edges on the inside of the fob casing to ensure a clean mating surface for gluing.
2. Test Fit: Before applying glue, test fit the two halves of the fob casing together (without the PCB initially, then with it) to ensure they close properly and align well.
3. Apply Glue: Apply a thin, even bead of plastic glue to the perimeter of one half of the fob casing.
4. Clamp and Cure: Carefully align and press the two halves of the fob together. Use clamps or rubber bands to firmly hold the casing together while the glue dries completely, following the glue manufacturer’s recommended drying time.

Re-sequencing Your BMW Key Fobs

After replacing the 2001 BMW key fob battery, you will likely need to re-sequence your key fobs to ensure they are recognized by your BMW.

1. Prepare Keys: Gather all your BMW key fobs. Designate one key as the “initial” key – this is just for clarity in the process.
2. Enter Vehicle: Get into your BMW, close and unlock all doors.
3. Initial Key Sequencing: Insert the “initial” key into the ignition and turn it to position 2 (ignition on, dash lights illuminated, but engine not started).
4. Button Press Sequence: Remove the key from the ignition. Immediately press and hold the unlock button on the key fob. While holding unlock, press the lock button three times in quick succession. Release all buttons.
5. Confirmation: The car’s Central Locking System (CLS) should respond by locking the doors and then unlocking the driver’s door to confirm successful sequencing.
6. Repeat for Other Keys: For each additional key fob, repeat the button press sequence (steps 4 and 5) immediately after sequencing the previous key.

Important Note: Any key not re-sequenced during this process will not function correctly. You will need to repeat the entire re-sequencing procedure to add any missed keys.

Troubleshooting and Tips

• Battery Sourcing: If you have difficulty finding a VL2020 battery with leads, consider purchasing a plain VL2020 battery and carefully reusing the leads from your old battery.
• Soldering Challenges: If you are not experienced with soldering, practice on some scrap electronics first. Ensure you have good lighting and a stable workspace.
• Fob Not Opening: If the fob is extremely difficult to open, apply gentle heat from a hairdryer to soften the glue slightly. Be careful not to overheat the plastic.
• Key Not Re-sequencing: Ensure you are performing the re-sequencing steps quickly and accurately. Double-check that your doors are unlocked before starting.

Replacing your 2001 BMW key fob battery is a rewarding DIY project that can restore your key fob’s functionality and save you money. By following these steps carefully, you can confidently tackle this repair and get back on the road with a reliable key fob.