How to Change BMW Key Fob Battery

For many BMW owners, the key fob is a crucial part of the driving experience, offering convenience and security at the push of a button. Over time, however, the battery within the key fob can weaken and eventually require replacement.

Understanding how to identify a weak battery, replace it, and even start your BMW with a dead key fob battery are essential skills for any BMW owner.

Published: February 27, 2024.

First Signs of Weak BMW Key Fob Battery

Recognizing the early signs of a weak key fob battery can prevent you from being locked out of your vehicle or facing difficulties starting it. Here are the most common indicators:

• Decreased Range: You may need to press the fob closer to the vehicle than before to lock or unlock the doors.
• Inconsistent Operation: The key fob sometimes fails to unlock the doors or trunk, or to arm/disarm the alarm system.
• Dashboard Warning: Some BMW models display a warning message or symbol on the dashboard indicating a low key fob battery.

Most Common Key Fob Batteries

BMW key fobs typically use CR2032 or CR2450 batteries. These are 3-volt lithium coin batteries known for their long shelf life and reliability, making them ideal for small electronic devices like key fobs.

How to Replace Your BMW Key Fob Battery

• Replacing the battery in your BMW key fob is a simple process that you can complete in just a few steps:
• Identify the Correct Battery Type: Check your owner’s manual or the existing battery to confirm whether it's a CR2032 or CR2450.
• Open the Key Fob: Use a small screwdriver or a coin to pry open the key fob. Some BMW key fobs have a slide or push button that releases the back cover or the internal key blade.
• Replace the Battery: Carefully remove the old battery and insert the new one, ensuring the positive side is facing up.
• Reassemble the Key Fob: Snap the key fob back together. Ensure it's securely closed to avoid damage or moisture entering the fob.

Do You Have To Reprogram BMW Key Fob After Battery Replacement

No, you typically do not have to reprogram a BMW key fob after replacing its battery. The key fob's programming is retained even when the battery is removed, meaning that it should work normally once the new battery is installed. Here’s why:

Key Fob Memory

The key fob contains a small chip that holds the security coding and programming necessary to communicate with your BMW. This chip is powered by the key fob's battery, but the information on the chip is not erased when the battery is removed. Instead, the chip is designed to retain this information indefinitely, regardless of whether it is powered.

Steps After Battery Replacement

After you replace the battery in your BMW key fob, the following steps are usually all that's needed:

• Test the Key Fob: After replacing the battery, test the key fob by locking and unlocking your vehicle. This ensures that the battery is properly installed and functioning.
• No Synchronization Required: For most BMW models, no further steps are required. The key fob should operate as expected without the need for reprogramming or synchronization.

Exceptions

While reprogramming is not typically necessary after a battery replacement, there are a few instances where additional steps might be needed:

• Older BMW Models: Some very old BMW models may require the key fob and the car to be re-synced. This process usually involves a specific sequence of actions, such as turning the ignition on and off a certain number of times or pressing the key fob buttons in a particular order. However, this is generally not the case for models produced in the last two decades.
• Key Fob Issues: If the key fob does not work after replacing the battery, ensure the battery is correctly installed (with the right polarity) and that the battery itself is not defective. If problems persist, there may be an issue with the key fob itself or the vehicle’s receiver.

For the vast majority of BMW models, replacing the key fob battery is a straightforward process that does not affect the programming of the key fob.

Simply change the battery, and you should be ready to use your key fob without any further action. If you do encounter issues after replacing the battery, consult your BMW’s owner manual or contact a BMW dealership for assistance.

Popular BMW Models and Their Key Fob Batteries

Different BMW models and years might use different key fob designs and batteries. Here’s a quick reference for some popular models:

BMW 3 Series (F30/F31/F34) 2012-2019: CR2032

The BMW 3 Series from 2012 to 2019, encompassing the F30, F31, and F34 models, utilizes a CR2032 battery in its key fob. This 3-volt lithium coin cell battery is known for its long life and reliability. The key fob design for this series is user-friendly, allowing for easy battery replacement by the owner.

BMW 5 Series (G30/G31) 2017-Present: CR2450

For the BMW 5 Series models G30 and G31, starting from 2017 onwards, a CR2450 battery is required. This battery is slightly larger in diameter compared to the CR2032, providing a higher capacity for the vehicles' more advanced key fob functionalities, such as increased range and additional convenience features.

BMW X3 (G01) 2018-Present: CR2450

The BMW X3, specifically the G01 model from 2018 to the present, also uses the CR2450 battery. The key fob for this model incorporates advanced technology, including comfort access and the ability to remotely start the engine, necessitating the higher capacity of the CR2450 battery to accommodate these power-intensive features.

BMW X5 (F15) 2014-2018: CR2032

For the BMW X5 model F15, spanning from 2014 to 2018, the key fob operates with a CR2032 battery. Despite its robust functionality, including remote locking/unlocking and tailgate control, the energy-efficient design of the F15's key fob allows it to operate effectively with the CR2032 battery.

BMW 1 Series (F20/F21) 2011-2019: CR2032

The BMW 1 Series models F20 and F21, produced from 2011 to 2019, require a CR2032 battery for their key fobs. These models feature a compact key fob design that provides essential functions like lock, unlock, and trunk release, efficiently powered by the CR2032's reliable performance.

BMW 7 Series (G11/G12) 2015-Present: CR2032 for Display Key, CR2450 for Non-Display Key

The BMW 7 Series, including the G11 and G12 models from 2015 onwards, presents a unique scenario. It offers two types of key fobs: a standard non-display key and an optional display key.

The non-display key uses a CR2450 battery, accommodating its conventional functionality. In contrast, the display key, which features a touchscreen display for additional controls and information, relies on a CR2032 battery. The display key's battery is rechargeable, and its inclusion in this list is for the sake of completeness and awareness for owners.

Please refer to your specific model’s manual, as battery requirements can vary based on the key fob design.

How to Start BMW With Dead Key Fob Battery

If your BMW key fob battery dies, you can still start your vehicle by following these steps:

• Access the Interior: Use the integrated mechanical key hidden inside the key fob to manually unlock the door.
• Position the Key Fob: In models with a start/stop button, hold the key fob against the steering column's marked spot (often with an RFID symbol). In older models with a key slot, insert the fob into the slot.
• Start the Vehicle: With the key fob in position, press the brake pedal (or clutch in manual transmission cars) and push the start/stop button to start the engine.

Few Final Words

Maintaining your BMW key fob by promptly replacing the battery ensures you can continue enjoying the convenience and security features without interruption.

By familiarizing yourself with the signs of a weak battery, knowing how to replace it, and understanding how to start your car with a dead key fob, you can avoid potential inconveniences and enjoy a seamless driving experience. Always refer to your BMW’s owner manual for detailed instructions specific to your model.