Is your 2001 BMW 325i key fob starting to act up? Do you find yourself pressing the buttons multiple times just to lock or unlock your doors? You’re likely experiencing a common issue: a dead or dying key fob battery. While some might believe the urban legend that these key fobs recharge while driving, that’s simply not the case. The solution is straightforward and you can easily tackle it yourself: replacing the battery. This guide will walk you through the process of a 2001 Bmw 325i Key Fob Battery Replacement, saving you time and money compared to dealership service.
Tools You’ll Need
Before you begin, gather these tools to make the 2001 bmw 325i key fob battery replacement process smooth:
- Vice-grips: To securely hold the key.
- Paint scraper: For initial prying.
- Sharp knife: To carefully slice and separate the fob casing.
- Small tipped soldering iron: For precise soldering.
- Silver solder: For creating strong electrical connections.
- Small chisel or pocketknife: To remove old battery leads.
- Wide jaw pliers (Channel-Locks): To hold the PCB.
- Rubber band: To apply gentle pressure to the pliers.
- Plastic glue: To re-seal the fob.
- Replacement Battery: Panasonic VL 2020 with or without leads (more on this later).
Step-by-Step Battery Replacement for Your BMW 325i Key Fob
This section details how to replace the battery in your 2001 bmw 325i key fob. Proceed carefully and patiently.
Opening the Key Fob
The first challenge in this 2001 bmw 325i key fob battery replacement is opening the glued-shut fob.
- Secure the Key: Hold the metal key part firmly with your vice-grips. This gives you a stable base to work with.
- Start Prying: Begin at the ring end of the fob. Use the paint scraper to wedge into the seam.
- Slice and Pry: Carefully use the sharp knife to slice along the seam while gently prying upwards. Work your way around the fob, slowly cracking the case open. Be patient and avoid excessive force to prevent damage.
Identifying the Battery
Once open, you’ll see the internal components. The battery is located on one side of the printed circuit board (PCB).
- Locate the Battery: Identify the round, metallic Panasonic VL 2020 battery.
- Note the Leads: Observe the custom leads tack-welded to the battery’s positive (+) and negative (-) terminals. These leads connect to the PCB.
Removing the Old Battery
Now, carefully remove the old battery to prepare for the 2001 bmw 325i key fob battery replacement.
- Secure the PCB: Grip the PCB with your wide jaw pliers. Use a rubber band around the handles to maintain gentle pressure – avoid squeezing too tightly to prevent damage.
- Desolder the Leads: Apply heat from your soldering iron to the back of each battery lead where it’s soldered to the PCB. Wait for the solder to melt, then gently pull the lead free. Repeat for both leads.
- Remove the Battery: Once both leads are desoldered, the old battery and its attached leads should be free.
- Detach Old Leads (Optional but Recommended): Use your chisel or knife to carefully pry the custom leads off the old battery. While you can buy replacement batteries with pre-attached leads, using just a plain VL2020 battery and reusing the original leads is often easier for soldering in this tight space.
Installing the New Battery
With the old battery removed, it’s time to install the new one as part of your 2001 bmw 325i key fob battery replacement.
- Solder the Negative Lead: Solder the negative lead (the one with the smaller through-pin) to the bottom (non-writing side) of your new VL 2020 battery. Use a minimal amount of solder to ensure a snug fit within the fob.
- Attach Negative Lead to PCB: Resolder the negative lead back into its original position on the PCB. The smaller pin size will help you identify the correct orientation. Ensure the battery sits centrally on the white insulating pad on the PCB’s front side.
- Solder the Positive Lead: Solder the positive lead to the top of the new battery and then to its corresponding point on the PCB. Double-check the orientation before soldering to ensure correct polarity.
Closing the Key Fob
The final step in the physical 2001 bmw 325i key fob battery replacement is reassembling the fob.
- Prepare the Fob Edges: Clean up any frayed edges on the fob casing to ensure a clean closure.
- Test Fit: Before applying glue, try mating the two halves of the fob together (without the PCB inside) to ensure they fit properly. Then, place the PCB back inside and test the fit again.
- Apply Glue and Clamp: Apply a thin bead of plastic glue to the perimeter of the fob casing. Clamp the two halves together using clamps or rubber bands. Follow the glue manufacturer’s recommendations for clamping duration.
Key Fob Resequencing
After the 2001 bmw 325i key fob battery replacement, you’ll need to re-sequence your key fobs to your BMW.
- Prepare Your Keys: Gather all your BMW 325i key fobs. Choose one key to be the “initial” key for sequencing purposes.
- Enter the Car: Get inside your BMW, close all doors, and ensure the doors are unlocked.
- Initial Key Sequencing:
- Insert the initial key into the ignition and turn it to position 2 (dash lights on, but engine not started).
- Remove the key from the ignition.
- Immediately hold down the unlock button on the key fob.
- While holding the unlock button, press the lock button three times in quick succession.
- Release all buttons. The car’s central locking system (CLS) should respond by locking all doors and then unlocking the driver’s door, confirming successful sequencing for this key.
- Sequence Remaining Keys: Repeat step 3 for each of your remaining key fobs.
- Test Your Keys: Test all your key fobs to ensure they are now working correctly with your 2001 BMW 325i.
Now you’ve successfully completed your 2001 bmw 325i key fob battery replacement and re-sequenced your keys. Enjoy the convenience of a fully functional key fob once again!
