Not that long ago I lost my only accessible set of keys to my Mazda 3 Sport. I have a spare set somewhere, but thought at the time that they were probably buried in the back of my storage locker in Chilliwack. Going out to Chilliwack to get them may have been an option if, you know, the key to the storage locker wasn’t also on the same keychain that was lost. Ultimately I had to tow my car to Mazda and get them to give me two new keys, both of which were entered into the onboard computer to allow them to actually start the car.

Since that time I’ve reclaimed the set of keys that were lost as well as my spare set of keys. That’s great in that I now have all those items back, but unfortunately neither the FOBs (the wireless units that open and close the doors) nor the keys work with my car anymore, since the onboard computer has been reset for the new items.

If you take them to a Mazda dealership, they will often charge to program the keys and the FOB, or so I’m told. Instead, I decided to scour the internet and eventually found instructions buried on a forum for how to do it.

For future reference, here is how you reprogram keys and FOBs for the Mazda (I believe it’ll work for the 3 and the 5, and possibly others).

Reprogram Keys

To allow a spare key to start the car, you need to start out with two working keys for the Mazda. This is security precaution to make sure someone with one key can’t activate another one, for example, a valet who has the key. If you only have one key, you’re out of luck and will have to take the car to Mazda to have it done. In fact, many people recommend buying a spare key and doing this procedure so that you always have three working keys around (you only receive two when you buy the car). That way if you lose one, you still have the ability to do this procedure on your own.

Here is how you do it:

  • Insert the first working key into the key slot and turn the ignition to ON. Wait about 5 seconds, then remove the key.
  • Insert the second working key into the key slot and turn the ignition to ON. Wait about 5 seconds, then remove the key.
  • Insert your new/spare key into the key slot and turn the ignition to ON. Wait about 5 seconds, then turn to OFF. This should add that key’s information to the onboard computer and allow it to start the car.

How To Reprogram the FOBs

This procedure is a bit more involved, and it reminds me a bit of the Konami Code from Nintendo. You’ll need access to all the FOB units that you want to enable for the vehicle. Apparently you can only have three active FOBs at the same time, so don’t try and program more than that.

  • Open the driver side door
  • Lock and then unlock the door using the button on the door. Leave the door open.
  • Insert a key into the ignition and turn the car to the ON position. Leave for about 2 or 3 seconds, then turn off. Repeat this two more times (3 in total). Leave the key in the slot in the OFF position.
  • Close the driver’s door. Then open it. Then close it. Then open it. Then close it. Then open it.
  • The onboard computer will respond by locking and unlocking all the doors at this point. That means it’s ready to accept FOB programming
  • Press a button on each FOB unit to program it to the computer.
  • When you are done programming FOBs, you can simply remove the key, which causes the computer to cycle the door locks once more.

I did both of these procedures in under five minutes, and now have four working keys and three working FOBs. So if you are in the same scenario and are feeling a little adventurous, you can simply reprogram the keys or the FOB yourself and save both time and money.

Where To Buy

I’ve tracked down a few links if people want to buy FOBs online.

For key blanks, here seems to be one that works with most models: