2007 Bmw 328I Key Battery Replacement – Restore Your Remote Entry

To perform a 2007 bmw 328i key battery replacement, you must first determine if you have a Comfort Access key (removable CR2032 battery) or a standard rechargeable key (soldered VL2020 battery). This guide provides step-by-step instructions for both versions to ensure your BMW’s remote functions and ignition compatibility are fully restored.

Few things are more frustrating than walking up to your E90 and realizing the doors won’t unlock. You press the button repeatedly, but the car stays silent and dark. You might even worry that a 2007 bmw 328i key battery replacement will require an expensive trip to the local dealership.

The good news is that most owners can handle this task at home with a few basic tools. Whether you have the convenient Comfort Access system or the standard rechargeable fob, we have you covered. This guide will walk you through the nuances of the BMW E90 key system so you can get back on the road.

In the following sections, we will identify which key you own and provide a clear path to success. We will cover everything from simple battery swaps to the more advanced soldering required for standard fobs. Let’s dive into the details and save you a significant amount of money in the process.

Identifying Your Key Type Before Starting

Before you purchase any parts, you must identify which key system your 328i uses. BMW used two distinct fobs for the 2007 model year. The method for a 2007 bmw 328i key battery replacement changes drastically depending on your specific hardware.

The first type is the Comfort Access key, which allows you to start the car while the key is in your pocket. These keys feature a small, rectangular battery door on the back. If you see a seam on the back of the plastic housing, you are in luck, as this is a user-serviceable design.

The second type is the standard non-Comfort Access key. These fobs are sealed at the factory and contain a rechargeable battery that draws power from the ignition slot. If your key lacks a battery door, it was never designed to be opened, but we can still fix it with a bit of patience and precision.

The Comfort Access Clue

Check your door handles for small ridges on the top surface. If your car has these ridges and unlocks when you touch the handle, you have Comfort Access. This system uses a standard CR2032 lithium coin cell that is easy to swap.

The Standard Rechargeable Fob

If you must insert your key into the dashboard slot to start the engine, you likely have the standard fob. These keys use a VL2020 Panasonic battery. This battery is soldered directly to the internal circuit board and charges while you drive the vehicle.

Essential Tools for 2007 bmw 328i key battery replacement

Having the right tools on hand will prevent damage to the plastic casing and the sensitive electronics inside. For the Comfort Access key, the list is very short. You likely already have what you need in your home tool kit.

For the standard rechargeable key, the process is more surgical. You will be opening a sealed plastic shell, which requires a steady hand. Here is a breakdown of what you should gather before you begin the 2007 bmw 328i key battery replacement process.

• For Comfort Access: A replacement CR2032 battery and a small flat-head screwdriver.
• For Standard Keys: A replacement VL2020 battery (with 90-degree solder pins).
• Cutting Tool: An X-Acto knife or a very thin utility blade for the standard fob.
• Soldering Equipment: A low-wattage soldering iron and some high-quality solder wire.
• Adhesive: Super glue or plastic cement to reseal the fob casing once finished.

Always work in a well-lit area with a clean surface. Small components like the transponder chip or the battery pins can be easily lost if they fall onto a dark carpet. Taking a few minutes to prep your workspace will save you hours of frustration later.

Step-by-Step: Comfort Access Battery Swap

If you have determined that your key supports Comfort Access, this is the easiest version of the 2007 bmw 328i key battery replacement. You do not need to worry about soldering or cutting plastic. The entire process should take less than five minutes.

1. Remove the Emergency Key: Press the small release button on the side of the fob and pull out the metal key blade.
2. Open the Battery Cover: Look into the slot where the metal key was stored. You will see a small tab or a notch. Use your flat-head screwdriver to gently pry the back cover away from the main body.
3. Remove the Old Battery: Use the screwdriver or your fingernail to pop the CR2032 battery out of its housing. Take note of the orientation; the positive (+) side should be facing up.
4. Insert the New Battery: Slide the fresh CR2032 into place, ensuring it sits flush against the metal contacts.
5. Snap the Cover Back: Align the plastic tabs and press the cover firmly until it clicks. Reinsert the metal emergency key.

Once the new battery is in, your car should recognize the key immediately. You may need to stand close to the vehicle for the first lock/unlock cycle to re-establish the connection. If it doesn’t work, double-check that the battery is seated correctly.

Advanced DIY: Replacing the Soldered VL2020 Battery

This section is for those with the standard, non-Comfort Access key. Since these fobs are sealed, a 2007 bmw 328i key battery replacement requires opening the shell along the factory seam. This is a delicate operation that requires extreme care to avoid slicing the internal circuit board.

Start by removing the emergency key blade. Using your utility knife, carefully score the seam that runs around the perimeter of the fob. Do not try to cut through in one pass. Instead, make several light passes to gradually weaken the plastic until the two halves can be pried apart.

Once the shell is open, you will see the green circuit board. The VL2020 battery is held in place by two solder points. Use your soldering iron to heat these points while gently lifting the battery. Be careful not to overheat the board, as this can lift the copper traces and ruin the remote permanently.

Position the new VL2020 battery so the pins align with the holes in the board. Apply a small amount of solder to create a strong electrical bond. Once the solder has cooled, place the board back into one half of the shell and test the buttons before applying any adhesive.

Finally, apply a very thin bead of glue around the edge of the shell and clamp the two halves together. Use minimal pressure to ensure the buttons still click properly. Let the glue cure fully for at least an hour before inserting the key into your ignition.

Programming and Resyncing Your BMW Key

In most cases, a 2007 bmw 328i key battery replacement will not cause the car to “forget” the key. The coding is stored in a non-volatile memory chip that doesn’t require constant power. However, sometimes the rolling code sequence gets out of sync.

If your remote buttons don’t work after the battery swap, but the car still starts when the key is in the slot, you likely just need a simple resync. This process tells the car’s computer to align its security codes with the new signals coming from your fob.

To resync, enter the car and close all the doors. Insert the key into the ignition slot and turn it to the “On” position (without starting the engine), then turn it off and remove it. Within 30 seconds, hold the “Unlock” button while pressing the “Lock” (BMW logo) button three times quickly.

Release all buttons. If successful, the door locks will cycle up and down automatically. This confirms that the central locking system has accepted the key. If you have multiple keys, you must perform this process for all of them during the same session to keep them all active.

Troubleshooting Common Key Fob Issues

If you have completed the 2007 bmw 328i key battery replacement and the key still fails to function, the problem may lie elsewhere. Automotive electronics are complex, and several components must work together for the remote entry to operate.

One common culprit is the Antenna Diversity Module, located near the rear window. This module receives the radio frequency signal from your key. If the module is failing due to moisture or age, even a brand-new battery won’t fix the range issues or the lack of response.

Another possibility is that the buttons themselves have worn out. Inside the fob, small tactile switches are soldered to the board. Over thousands of presses, these switches can crack or lose their connection. A skilled DIYer can often reflow the solder on these switches to bring them back to life.

If the key won’t start the car at all, the EWS (Immobilizer) chip may be damaged. This chip does not rely on the battery for power; it uses an induction coil around the ignition slot. If this chip is dead, you will unfortunately need to order a new, pre-programmed key from a certified BMW parts department.

When to Call a Professional

While we love a good DIY project, there are times when it is safer to seek professional help. If you are uncomfortable with a soldering iron or if you accidentally damage the circuit board during the shell-opening process, a local independent BMW specialist can often help.

There are also specialized locksmiths who focus on European car keys. They have the equipment to cut new blades and program the CAS (Car Access System) module. This is often significantly cheaper than the $300 to $500 price tag you might find at a dealership.

If you see smoke or smell burning plastic while soldering, stop immediately. Short-circuiting the battery can cause it to vent or leak, which is a safety hazard. If the fob feels excessively hot after the battery swap, remove the battery and consult an expert to check for internal shorts.

Frequently Asked Questions About 2007 bmw 328i key battery replacement

How long does the rechargeable battery usually last?

The original VL2020 battery in a non-Comfort Access key typically lasts between 10 and 15 years. Since the 2007 328i is now well beyond that timeframe, most original keys are reaching the end of their natural lifespan.

Can I use a regular CR2020 instead of a VL2020?

No. A CR2020 is a standard lithium battery, while the VL2020 is a vanadium pentoxide lithium rechargeable cell. If you put a non-rechargeable battery into a charging circuit, it could leak or explode inside your key fob.

Will my seat and mirror presets be lost?

Generally, no. Your personal profile settings are stored in the car’s memory, linked to the key’s unique ID. Replacing the battery does not change that ID, so your settings should remain intact after the swap.

Why does my key only work when I am right next to the car?

This is a classic sign of a weak battery. If you have already performed a 2007 bmw 328i key battery replacement and the range is still poor, check for window tint that might be blocking the signal or inspect the diversity antenna module.

Can I buy a cheap key shell on the internet?

Yes, if you have to cut your original shell open, buying a fresh aftermarket key housing is a great way to make the key look brand new. Just ensure you transfer the circuit board and the transponder chip carefully to the new case.

Final Thoughts on BMW Key Maintenance

Taking care of your 2007 BMW 328i means staying on top of the small details. A 2007 bmw 328i key battery replacement is a perfect example of a minor maintenance task that significantly improves your daily driving experience. No more fumbling with the manual door lock in the rain!

Whether you took the easy route with a CR2032 or tackled the soldering challenge of the VL2020, you have demonstrated the resourcefulness of a true enthusiast. Keeping these older E90 models on the road is a rewarding endeavor that keeps your wallet full and your car functional.

Remember to always test your spare key periodically. It is much easier to fix a dying battery when you have a secondary way to drive the car. Stay proactive with your maintenance, and your BMW will continue to provide that ultimate driving machine experience for years to come. Stay safe and happy wrenching!