Changing the Battery in Your Mazda 3 Key Fob

It's frustrating to pull into your car at the end of a long day and find that the key fob is dead. Fortunately, it is simple to fix it with simple battery replacement from an electronics store or big box retailer.

A spare key fob for your Mazda 3 is an inexpensive way to avoid having to take your vehicle to a dealership to have them re-program the keys.

Battery Replacement

You can change the battery on your Mazda 3 keyfob at home. However, you should replace the battery when it goes out of service, or if the key fob displays a message in the multi-information display, "Low key fob battery. 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 portion of the metal of the Mazda 3's key fob and then insert the tip of the screwdriver in it to remove the lower part. Repeat the procedure for the top piece of metal but be careful not to damage the rubber ring at the bottom of the case.

Once the fob case is open, you'll see the slots on either side of the case that houses the battery. Use the flathead screwdriver with tape to gently open the case, starting on one side and then moving to the opposite. Take out the old CR2025 and replace it with a new one, making sure that you put it on its face to ensure proper orientation. Place the battery cap on the other side and attach both sides of your key fob case by pressing until they click.

Now that you've replaced the battery Test the fob to verify that it is working by locking and unlocking your doors. If everything appears to be working then you can begin using the Mazda 3's remote functions in the road!

Pairing Issues

If your key fob has stopped working all of a sudden it could be because the transmitter in the car has been damaged. It's usually a task for a professional, and you will require a brand new key fob.

If you've tried replacing the battery and programming the key fob but does not solve the issue it could be that the chip in the key fob may be defective. This can happen if the keyfob was dropped or exposed to saltwater or was touched by dirty fingers.

To identify the issue, you will need to locate a tiny "key" built into the edge of the fob that lets you open it up and take out the circuit board. You will then be able to look for any damage or corrosion on the chip. It is recommended to use a clean towel to avoid damaging the microchip.

If you are unsure it is possible to check the battery connector terminals for cracks or broken. If this is the case, then carefully connecting them back can usually restore the function of the key fob. Additionally, you can look at the buttons to determine if they are worn or damaged. If the buttons are loose, they can easily be soldered back as well unless the button has actually snapped off.

Interference Signals

Few things are more annoying than gazing at the "No Fob Detected" message when trying to start your vehicle. This typically happens at most unpopular time, such as when you are late for work or if you're picking up kids from daycare or school. The good news is that there are steps you can take to investigate the issue and figure out what is causing it.

Interference signals can disrupt the remote key fob's signal from the vehicle which causes it to not function properly. This can be caused by things like buildings, weather conditions and transmitters that use the same frequency. Interference may also occur if you install aftermarket equipment in the vehicle that transmits at the same frequency as the key fob.

In addition, if your key fob is exposed to salt or seawater, it may be damaged. Water can penetrate the rubber seals of the electronic chip, especially in the event that the key fob is submerged in water for a lengthy time. The chip may stop working and require replacement of the keyfob. If you have a key that has the ability to be programmed, you can clean it with isopropyl or electronic cleaners to bring it back to its original functionality. If this doesn't work you can be sure that the chip has burned out and needs to be replaced.

Locking/Unlocking the Doors

The key fob's buttons send electronic signals to a solenoid in the car. It converts the signal into a mechanical action that locks and unlocks doors. If the door lock isn't working, it could be a solenoid issue that requires some investigation by an expert repair shop for autos.

A dead battery of 12 volts can also stop the fob from functioning properly. This could happen if your battery loses its charge or if the contacts become corroded. This issue can be solved in just a few minutes by purchasing a new battery.

If the key fob isn't working after you replace the battery or reprogram it then the problem may be in the receiver module. The device interprets radio frequency signals transmitted by the key fob to control the vehicle. It can be expensive to repair if it is damaged.

To test if this is true, insert your spare key into the key slot. Then, turn the ignition ON. Press the key fob two times in 10 seconds, without taking it out. The mazda keys replacement 3 system synchronizes the key to the vehicle and you can use it as your primary driving remote. You can program up to three keys this way.