Key Fob Details, Covers & Batteries

[updated 6/10/2018, 9/27/2018, 7/15/2019, 3/26/2021, 5/28/2021]

key fob fiat1.jpg

The 3-volt coin battery in your key fob needs to be near it’s rated output, in order for all of the functions to work properly:

Remote Keyless Entry (RKE) functions…

  • doors (and fuel door) lock/unlock
  • trunk release (in some markets)
  • panic (in some markets)

and if you have the Advanced Keyless Entry (AKE) option (no need to remove your key from your pocket/purse) – you gain these additional features…

  • allowing you to push a button on the door handle to lock/unlock
  • allowing you to push a button on the underside of the decklid (next to the rear-view camera) to release the trunk
  • allowing the walk-away locking feature

and Advanced Security system activation/deactivation – if your vehicle is equipped with the option.

Don’t store the key fob in/near the vehicle!

It is not a good idea to have the key fob in (or near) the vehicle when parked, as the vehicle battery will discharge quicker, since the vehicle is unable to go into Deep Sleep mode with the key fob close by.

“Low” key fob battery

key fob battery low

On average, you should get about 2 years usage out of a good quality battery.  When the START/STOP button is pushed from ON to ACC or OFF position, and the cluster Key Indicator Light flashes green for approximately 30 seconds, it’s time to replace your “low” key fob battery (should do both fobs), so that you’ll avoid a…

“Dead” key fob battery

as evidenced by:

  • you are unable to start the car unless you use the logo end of the fob itself to push in the start button
  • the cluster Key Indicator Light (between the speedometer and the tach, shown above) is red

☑  There is a RFID chip in your fob that is not dependent on the fob battery, and that is part of the passive immobilizer system that requires you to have the key in very close proximity to the start/stop button, in order to start the vehicle.  Until the fob battery is replaced, you can start your vehicle by pushing the start button with key fob (the end with the logo; not the emergency key end).

fob low battery

In either case, you will need to replace the batteries by first purchasing a couple of new CR2025 batteries (even if one of your fobs has been sitting in a drawer unused, you are advised to replace the battery in both of your fobs).

Some have reported that a 2032 battery will also work (and may outlive the 2025 batteries by a few more months), but since it is 3.2 mm thick (vs. 2.5 mm), depending on where the ground contacts are incorporated into the battery “pouch”, it may spread the ground contacts, such that 2025 batteries will no longer work reliably in the future.

Here is a nice YouTube video that demonstrates how to open up your key fob, stressing that you must start by first prying apart the two sides in an inner area first (where the emergency key resides), in order that you not break any tabs in the shell case.  Here is a summary of the steps involved:

  • The first step is to turn over the fob and locate the plastic release tab.
  • Slide the release tab {1} to release the metal emergency key from the fob.
    key fob3
  • Remove the metal emergency key {2} and set it aside in a safe place.
  • Insert the small flat head screwdriver in to the sides of the cavity of the fob in between the two halves.
    key fob1
  • Gently pry off the rear cover {4} of the fob.
    key fob2
  • Then use the screwdriver to gently pry off the round black plastic battery cap {5}.
    key fob4
  • Either turn over the fob and gently tap out the old CR2025 battery {6} or remove it with the blade of the small flat head screwdriver.
    key fob5
  • Try to avoid bending the metal electrical contacts or scratching the green circuit board
  • Insert the new CR2025 battery in to the socket with the “+” positive side facing up and the “-” negative side facing down.
  • Make sure that the new battery is securely seated in the holder.
  • Push the plastic battery cap back in to place.
  • Line up the back cover with the other half of the fob and gently pop them back together.
  • Make sure that the two halves of the fob are flush together at every edge.
  • Slide the metal emergency key back in to its slot.
  • To test the new battery, stand near your car and press the “Unlock” or “Lock” buttons.
  • If the new battery is working properly, the parking lights should flash and you’ll also hear the door locks opening or closing.

☑  If you choose to keep a spare battery in your armrest cubby coin slots, it would be best to keep other coins out of that area.

Emergency Key

As you may have read in the instructions above, there is an actual (emergency) key hidden in each fob, that will open/lock your driver door and the storage cubby.   There is a release tab on the rear side of the fob that releases the key, as shown in the Step 1 photo above.

☑  Note that without a working fob, you won’t be able to disable the anti-theft alarm (if equipped).
key fob

Key Fob Specs

After seeing questions regarding replacement keys, I added a Key Specs section to my Specifications page on 6/8/2018, the most critical # being the FCC #, which must match.  After purchasing, you will need to have a locksmith or the dealer program the fob to your VIN #, as well as cut the emergency key* to mate with your door lock (the cubby lock isn’t so particular).

Key Fob Model #: SKE13D-01
Key Fob FCC #: WAZSKE13D01 (or WAZSKE13D02)
Key Fob battery


There have been several reports that Mazda fobs having the same FCC number were purchased as replacements, primarily because they are more plentiful and priced significantly lower, and although the fob functions in the 124 Spider, nevertheless, a variation is detected that results in an annoying red display of the cluster Key Indicator Light.

Key Fob Covers

keyfobAnyone looking for key fob covers for the Fiat/Abarth 124 Spiders might consider these silicone covers that instead of having a Mazda logo (since Fiat logo covers aren’t available yet), there is a cutout that allows the (Fiat) logo on the fob to appear.  I see that they are available on Amazon now, and there are other color combinations available as well.

Not only do they help protect the fob, but they do a good job of keeping the fob from sliding out of your pocket while sitting.

Key Ring Doodads

key rings

It might be best to avoid certain key rings doodads, which hang perpendicular to the fob buttons, so for those carrying their fob in their pocket (most men), you are quite likely to accidently lock/unlock or set off the panic button.

Key Fob Replacement shell case/key blank


If your circuit board is OK, but you would like to replace the key fob shell case and/or the button pads, or need an uncut key blank, check out this kit at Amazon for around  $15.

  Suzan tried to have her dealer cut the key for her, but gave up…

I was able to go to a local locksmith and for $5 have the key cut solving the problem. I called the dealer to let them know that this possible.  Matt the service guy said he had no idea you could do that.  The locksmith told me that some locksmiths have the ability to use the Vin# to cut a key too.  This takes longer as they must verify that you are the owner of that vehicle.  All good info for the future.

So for $20 total outlay, vs. $350 (+ $100 to program) that your Fiat dealer wants, you can replace your missing emergency key and/or your broken fob case!

10 thoughts on “Key Fob Details, Covers & Batteries

  1. lost my key fob ,sat it on roof and got distracted and drove off luckily noticed and drove back home and got spare without turning off car but alas could not find lost fob .
    In Australia new fob 1200 dollars so got the mazda one got key cut and fob programmed all good for 250 dollars
    but the redkey light stays on dash scan tool shows B13 D34 a codes ic there a work around .


    • Peter, you aren’t the first to report back that the Mazda fob, although it functions, doesn’t totally integrate with the electronics. I’ve added the following note to my Key Fob Specs, as well as this Key Fob article, so that this result is anticipated:

       There have been several reports that Mazda fobs having the same FCC number were purchased as replacements, primarily because they are more plentiful and priced significantly lower, and although the fob functions in the 124 Spider, nevertheless, a variation is detected that results in an annoying red display of the cluster Key Indicator Light.

      My first inclination, is to make your new purchase the SPARE key, and hopefully the light and codes can be reset until you use that fob again.


  2. All I require is the front plastic fascia as it is cracked. The rest of the fob is fine! Sadly, my fob has a centrally positioned battery – not like the one that you refer to on Amazon. This means that the replacement shell is unsuitable for my fob! Any ideas?


    • Steve, you’re right. I never noticed that before – just that the buttons appeared to be the same. Let’s see if we can locate the proper shell replacement…


      • There is a possibility that I may have found one on eBay – but it is not associated with the 124 nor the MX5 (Miata in the US). It seems to be for the larger Mazdas, but looks the same. I will let you know how I get on (I am from the UK, by the way)


      • OK, I’ve updated the Amazon link to what appears to be the proper shell replacement. 😉
        If your ebay purchase works out, and it looks like it’s a stocked item, I’d be happy to add the link for UK readers.


  3. I have the replacement shell! And it appears compatible. However, I need to replace the broken fascia on MY key (which still works fine) with the new fascia! My buttons are not broken…just the black plastic surround! How do you do that? I can easily take the back off to access the battery, but I have no idea how to remove the back…safely! Can you help?


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