BMW key fobs have come a long way, evolving from basic metal keys to advanced smart devices. Let’s take a closer look at how their designs and capabilities have changed over the years and learn tips for replacing your key fob’s battery.
Early BMW Key Fob Designs
The earliest BMW key fobs appeared in the 1980s. Unlike today’s devices, these were merely plastic casings around the base of the metal key. These early key fobs had holes that could fit key rings, making it easier for drivers to organize their keys and reducing the risk of falling off.
Despite their simplicity, the early key fobs improved upon ordinary keys.
First, their plastic surfaces were less slippery than bare metal, making it less likely for the driver to lose their grip on the key. Second, the key fobs gave the veneer of a premium appearance to the admittedly simple-looking keys. Third, they bore the BMW logo, helping drivers who owned multiple cars to identify which key belonged to a particular vehicle.
During the 80s, BMW added a keyless entry system to its top-of-the-line luxury cars. Some models had a bulky remote that wirelessly locked and unlocked the doors.
In the 90s, BMW introduced some minor changes to the key fobs for its cars. Some BMW key fobs had a tiny light. Pressing the button activated the light, which provided enough illumination to find the keyhole at night.
The Rise of the Modern Key Fob
BMW began introducing what you’d recognize as modern key fobs with models like the BMW E39 and BMW E46. These key fobs had buttons that remotely locked and unlocked the doors.
It took a while for BMW key fobs to adopt the keyless start feature. Early BMW models with push-button ignition required you to insert the fob into the ignition and step on the brake pedal before starting the engine.
Eventually, BMW introduced the Comfort Access system. The key fob emits a signal telling the car to unlock the door once you touch its handle. You can start the car by stepping the brake pedal and pushing the Start button.
In the 2010s, the BMW i8 and BMW 7 Series introduced smart key fobs with a small LCD touchscreen. These key fobs can operate climate control and other systems. On hybrids, the smart key fob’s screen displays the charging status.
In European models of the BMW 7 Series, the smart key fob can remotely park the car while you remain outside. It’s very different from the simple key fobs from the 1980s.
How to Replace the Battery in a BMW Key Fob
A key fob is a convenient device that lets you unlock and lock your car’s doors, operate the car alarm, and perform a keyless start outside the vehicle. However, the key fob uses a battery that eventually runs out of juice. If that happens, you’ll have to replace the BMW key fob battery.
There are two types of BMW key fobs according to their shape. The rectangular type conceals a physical key inside its body. The other type is a diamond key fob, and its key protrudes from the device’s front. The steps for accessing the battery will differ depending on the type of key fob you’re working on.
Rectangular BMW Key Fob
Check the back cover of your BMW key fob. You’ll find a button on the cover. Press this button to release the physical key hidden inside the fob.
This physical key is a backup that lets you operate your BMW’s doors and ignition system if the key fob develops an issue that prevents it from working properly. It’s also the sole tool you’ll use to replace the key fob battery.
Look for the tab that releases the back cover from the key fob. Insert the physical key into the release tab and gently pry the cover off, using the key as a lever. Then, pull away the back cover to reveal the circular-shaped battery.
Remove the battery from the BMW key fob. If the battery seems stuck, use the physical key to pry it out.
Diamond BMW Key Fob
You can’t separate the physical key from a diamond-shaped key fob. You’ll need a substitute tool to remove the back cover and the battery.
Get a screwdriver with a flat head. Insert the screwdriver into the release tab that secures the cover to the key fob’s back. Gently pry the back cover off.
Installing a New Battery
Now it’s time to put the replacement battery in the key fob. Ensure the battery’s positive side is facing upward when you fit it in the fob.
Fit the back cover on the key fob. Make sure the cover fits tightly to prevent it from falling off the fob, exposing the battery which might drop out in turn.
For rectangular key fobs, return the physical key to its slot in the fob. Similar to the back cover, check if the key fits snugly and won’t slide out unless you press its release button. If you own a diamond key fob, you don’t have to worry about its key.
Finally, test the key fob. Press the buttons to lock and unlock the doors. If the key fob can turn on the engine, try that function as well.
When Do You Need to Replace the Key Fob Battery?
You might need to install a new battery in your BMW’s key fob when your car fails to respond to the signals from the device.
For example, pressing the lock button on the key fob should engage your car’s door locks immediately. But if the fob’s battery is low on power or develops an issue, the device might have trouble sending the signal out. The fob might transmit a weaker signal or not send any, delaying or preventing the locking process.
Tools for the Job
If you’re working on a rectangular BMW key fob, you only need a replacement battery. BMW key fobs use the CR2450 battery.
To replace the battery in a diamond BMW key fob, you’ll need a flathead screwdriver or a similarly flat tool.
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