Changing the Battery in Your Mazda 3 Key Fob

It's frustrating to drive off at the conclusion of a long and tiring day and find that the key fob is dead. Luckily, it's an easy fix by purchasing an easy battery replacement at the hardware store or big box retailer.

A spare key fob for your Mazda 3 is an inexpensive way to avoid having to take it to a dealer to have them reprogram the keys.

Battery Replacement

You can change the battery on your mazda key fob 3 keyfob at home. However, you should replace the battery if it dies, or if the key fob shows a message on the multi-information display stating, "Low key fob battery. Replace battery."

You'll need a flathead screwdriver and tape and patience to open the case. The head of the flathead screwdriver in a notch or gap on the bottom of the metal of the Mazda 3 key fob to take off the lower portion. Repeat the procedure for the top piece of metal, but be sure not to damage the rubber ring at the bottom of the case.

There's a slot each side of the case that houses the battery. Start with one side of the case, and then gently push it open. Remove the old battery and then put in the new CR2025, making sure that it's facing up to ensure proper polarity. Finally, place the battery cap back on and reattach both sides of the key fob case. Keep pressing until you hear them click.

Now that you've replaced the battery Test the fob to ensure it works by locking and unlocking your doors. If everything looks good, your Mazda 3 remote features can be used again.

Pairing Issues

This could be a sign that the transmitter in your car is damaged. It is typically a need for an expert repair and will likely require a new key fob.

If you've tried to change the battery and reprogram the key fob but it hasn't worked, the chip inside the key fob might be defective. This can happen if the keyfob has been dropped, exposed to saltwater, or was touched by dirty fingers.

To identify the issue it is necessary to find a small "key" that is embedded into the fob's seam that lets you open it up and take out the circuit board. You will then be able to examine for any damage or corrosion on the electronic chip. It is recommended to use a clean, dry paper towel to prevent damaging the microchip.

If you are unsure then you should also examine the battery connector terminals for cracks, or breaks. If this is the case it is possible to solder the terminals back into place will typically restore functionality to the key fob. You can also examine the buttons for wear or damage. If the buttons are loose, they can easily be soldered back in the event that a button has physically snapped off.

Interference Signals

Few things are more annoying than gazing at the "No Fob Detected" message when you attempt to start your car. It typically happens at most difficult time, such as when you're late for work or when you are picking up your children from daycare or school. There are several things you can try to figure out what's causing the problem.

Interference signals can disrupt the remote key fob's signal to the vehicle making it unable to work correctly. It can be caused by things like weather conditions, buildings and transmitters using the same frequency. Interference can also occur if you have an aftermarket device installed in the vehicle that transmits at the same frequency as the key fob.

The key fob could be damaged if it is exposed to salt water or water. The rubber seals on the chip's electronic components can be shattered by water, especially when it is submerged over an extended period of time such as in the ocean or a pool at the beach. The chip may stop working and require replacement of the keyfob. If you have a programmable key you can clean the chip with isopropyl Alcohol or an electronic cleaner to aid in its return to working. If this doesn't work, it is likely that the chip has fried and will need to be replaced.

Locking or Unlocking the Doors

The key fob's buttons send electronic signals to the solenoid inside the car. It transforms the signal into a mechanical action that locks and unlocks the doors. If the door lock does not work it could be because of an issue with the solenoid. This will require experts from auto repair shops to investigate.

A dead 12 volt battery could also prevent the fob from functioning properly. This can happen if the battery loses its charge or if the contactors are corroded and stop transmitting electricity. This problem can be fixed in minutes with a new battery.

The receiver module may be the problem if the key fob isn't working after you replace the battery or re-program the device. This device interprets radio frequency signals received by the key fob to control the vehicle. If it fails it could be costly to repair.

To test if this is true, put your spare key into the key slot. Then, turn the ignition on. Press the key fob button three times within 10 seconds without removing it. The Mazda 3 system synchronizes the key with the vehicle and you can use it as your primary remote for driving. You can program up to three keys this way.