It's The Ugly Truth About Mazda 6 Key Fob Changing the Battery in Your Mazda 3 Key Fob

It is frustrating to pull into your car at the conclusion of a long and tiring day and discover that the key fob is dead. This is a simple fix that is easily done at a big box retailer or at a hardware store.

Incorporating a spare key fob to your Mazda 3 can be an affordable way to keep yourself from having to be towed to the dealership and having them re-program your keys.

Battery Replacement

You can replace the battery on your Mazda 3 keyfob at home. You should only replace it when the battery fails or you see a message saying "Low keyfob battery" on the multi-information display. Replace battery."

To open the key fob case, you'll need a tape-wrapped flathead screwdriver and a bit of patience. Find a gap or notch in the bottom part of the metal of your Mazda 3's key fob and then insert the head of the screwdriver in it to remove the lower portion. Repeat this process for the top part of the metal however, be careful not to damage the rubber ring at the bottom of the key fob's case.

You'll find a slot on the opposite side of the case that contains the battery. Start on the other side of the case and gently push it open. Remove the old CR2025 and replace it with a brand new one, making sure to place it face-up to ensure proper orientation. Put the cap of the battery on the other side and attach both sides of your key fob case by pressing until they click.

After replacing the battery after replacing the battery, lock and unlock your doors to verify whether the fob is working. If everything looks good then you're able to use the Mazda 3's remote functions for the first time!

Pairing Issues

This could indicate that the transmitter in your car may have been damaged. This typically requires an expert to repair it and may need a new key fob.

If you've tried replacing the battery and reprogram the key fob but it hasn't worked then the chip in the key fob may be faulty. This could happen if the keyfob was dropped, exposed to saltwater, or was touched by dirty fingers.

To determine the cause of the issue, you will need to locate a tiny "key" embedded in the edge of the fob that lets you open it up and remove the circuit board. You can then examine the electronic chip for corrosion or damage. It is best to clean the paper towel to prevent damaging the microchip.

If you aren't sure, you can also check the battery connector's terminals for cracks or broken. If this is the situation, soldering the terminals back to their original position will usually restore functionality to the key fob. You can also examine the buttons for damage or wear. If mazda 3 lost key are loose, they can be re-soldered regardless of whether the button is actually snapped off.

Interference Signals

Few things are more annoying than gazing at a "No Fob Detected" message when you attempt to start your car. This happens at the worst time, for instance the time you're late to work or pick up your children from school/daycare. There are a few things you can do to help figure out what's causing the issue.

Interference signals can cause the remote key fob to stop functioning properly. This could be caused by objects such as weather conditions, buildings, and transmitters that use the same frequency. Interference can occur when your vehicle is equipped with aftermarket equipment that transmits at the same frequency as your key fob.

In addition, if your key fob is exposed to salt or water seawater, it may be damaged. The rubber seals on the electronic chip could be damaged by water, especially in the event that it is submerged for long periods of time, such as in a pool or at the beach. This could cause the chip's function to cease and will require replacement of the key fob. If you have a programmable key, you can clean the chip with isopropyl alcohol or an electronic cleaner to help it come back to normal. If this doesn't help, it is likely that the chip has been damaged and must be replaced.

Locking and Unlocking of Doors

The buttons on the keys send electronic signals to a solenoid within the car that then converts the signal into a mechanical action that locks and unlocks the doors. If the door lock isn't working, it may be a solenoid issue that requires investigation by a professional auto repair shop.

A dead 12 volt battery could cause the fob to stop functioning correctly. This is the case if the battery loses charge or if the contactors become corroded and stop conducting electricity. The good news is that a new battery is able to solve this issue in only minutes.


The receiver module may be the reason why the key fob doesn't work after replacing batteries or reprogram the device. The device receives radio frequency signals from the key fob and interprets them into controlling the functions of the vehicle. If it malfunctions it could be costly to fix.

To check if this is the case, begin by putting your spare key into the key slot and turning the ignition to ON. Press the key fob button twice within 10 seconds without removing it. The Mazda 3 system synchronizes the key to the vehicle, and you can now use it as your primary remote for driving. You can program up to three keys in this manner.