5 Reasons Why BMW Key Fob not Working After Battery Change

If you have just changed the battery of your BMW Key fob, but it still refuses to work, there are a couple of things that could be wrong with it.

It may be that you have replaced the dead battery with a bad one, or there is an issue with the buttons or terminals, or maybe it needs to be reprogrammed. 

The good news is that you can easily fix these issues. 

In this blog post, we will look at some causes affecting your BMW keyfob. Will will also examine various do-it-yourself methods to help you fix it.  

How does your BMW Key fob work?

The key bob is an important part of your vehicle security. It helps you to unlock and lock your car by pressing a button.

So, how does it work?

A battery powers your BMW key fob. It is programmed to work just for your car. That means even if you get a new key, you must program it before it can work.

Your BMW function uses a radio frequency Identification system (RFIS). The system works using an electromagnetic field between your key fob and a tag within your vehicle.

The RFID in your car sends a signal to your key fob; if it matches, the car will open or lock.

Why is your BMW key fob not working after a battery change?

It’s not strange if your BMW keyfob isn’t working, especially if you just changed the batteries.

Here are some reasons why your BMW key fob isn’t working

Loose Buttons

Loose buttons may cause the key fob not to work properly. Your BMW buttons are made of rubbers prone to wear and tear over time. 

Some buttons of your key fob may appear loose or shaking, and some will require you to press down hard before they work. 

In such a situation, you should get the buttons replaced by an authorized dealer or the keyfob replaced completely.

It is also possible that debris is stuck between the buttons. Try clearing it with a brush.

Faulty Connector Terminal

The battery connector terminal of your BMW keyfob may be bad. To confirm, you must take the remote apart and inspect the terminal.

Search for signs of rust or loose terminals and fix or replace them. You may need to solder the loose terminal in place.

Bad Batteries

I have seen situations where the replaced batteries are bad. It can be frustrating, especially when the batteries are new.

Confirm that the batteries are good and supplying power to your key fob. You can use the everyday multimeter to check.

Electrical Faults

It is possible that the cause is not your key fob but rather an electrical issue with your car.

For instance, if the door panel has been worked on, a wiring connection has been tampered with, or a wire is broken. The door may not respond to the key fob.

Most of the time, this fault will be associated with other faults and the key fob not working well. The remedy is to have an automotive electrician have a look.

Reprogramming Issue

Your BMW key fob is programmed for security purposes. Changing the battery may cause the fob to reset and become inoperable. 

In such a case, all other remotes, including the extra, will also stop working entirely. To remedy this problem, you must reprogram your BMW’s key fob.

How do you program your BMW Key fob?

Reprogramming your BMW key fob can be done easily by following these steps

  • Enter your BMW cabin with your key and key fob. Ensure all doors are locked and windows shut.
  • Insert your key into the ignition and turn to position one. Do not start the car.
  • Turn the key back to position zero and remove the key.
  • Using the key fob you want to program, press the unlock button, press the BMW logo three times and release. 
  • You should hear the doors lock and unlock.
  • Hold the unlock button and press the BMW logo three times if you have an extra key. You hear the door unlock and lock again.

Your key fobs are now reprogrammed and should work perfectly.

How do you inspect the condition of your key fob?

If you are uncertain about what is wrong with your key fob, follow these steps to inspect the fob physically. 

  • Using a disassembly tool, gently push and tilt open the key fob. Note, do not open the key fob from the top. Start from under and gently work your way to the top till it pops open.
  • Inspect the key fob for water. Your BMW key fob is designed with a system to let you know water has penetrated it.
  • Check the left top corner of the key fob. You will see a little circle. If the circle is white, it means there is no water ingression. However, if it is red, it means there is water.
  • Inspect the condition of the battery. Check for swellings on the battery. If there is any swell or physical damage to the battery, you may need to replace it with a new one.
  • Using a ZTS Multi-battery Tester MBT-1, check the battery voltage.

See: https://static.nhtsa.gov/odi/tsbs/2018/MC-10150896-9999.pdf 

Frequently Asked Questions (FAQ)

How do I know which battery my Key fob uses?

You can use the previous battery as a sample for the new one you want to buy. Check the Key fob for an example. You can use the battery serial number to find a new one for your key fob.

Final Thought!

In conclusion, you should be able to troubleshoot the cause of your BMW key fob not working.

Be sure to examine your key fob for some of the causes in this blog post. If the key fob still doesn’t work, it may mean that the signal produced by the key fob is low. You will have to request a new one from your BMW dealership.

Thank you for reading, and I hope you find it very helpful!

  • Edmond Davis

    I'm Edmond Davis, an automotive expert with years of experience in vehicle repair, performance, and safety. I graduated from the University of Michigan with a degree in Automotive Engineering and have worked with major companies like Ford, GM, and Chrysler. I'm a trusted source of information for anyone looking to learn more about cars or improve their driving experience.