Changing a Ford Focus (2002) Key Fob Battery

Last week the remote locking on my aging Ford Focus gave up the ghost; the manual locks still worked but the key fob no longer activated, all of which pointed to a simple flat battery in the key fob.

Normally the batteries in the key fob will last several years so it's likely (as in my case) that many Ford owners will not have needed to change the battery - hence a quick pictorial guide as it's not always obvious how it's done.

How to change the battery in a Ford Focus 2002 key fob

Step one:  You'll need your key without its keyring (not essential but makes life easier) and a small, flat-bladed screwdriver.

Step Two:  Turn the key over so the buttons are underneath.  The release catch for the key fob is in the middle of the fob just below the Ford logo.  Gently insert the blade of the screwdriver and apply some pressure to depress the catch, then gently ease the two halves apart.  If it's anything like my key there may be a fair amount of grime under there, so it could be a bit stiff to start with.

Step Three:  A gap will appear as the key halves slide apart and eventually...

Step Four:  ... you'll have two separate parts in front of you.

Step Five:  The next stage is to prise the fob apart - use your screwdriver to unhook the catches along the side...

 Step Six:  ... until the two parts are separated and you can access the battery.  It's a standard 2032 battery which you can find in any supermarket or DIY shop (I picked up mine for 78p incl. delivery from Amazon UK).

Step Seven:  Carefully prise the old battery out and replace with the new one.  Take care not to snap the retaining catches which hold the battery in place - these can be a bit stiff too but gentle pressure will seat the battery correctly.

Step Eight:  The final task is to put the key fob back together again.  First snap the two fob halves together, then slide the main fob into the key unit.  Make sure it's the right way up -the two highlighted sections should fit together.

Hopefully this will solve your problem, but you may be like me and find that even once the battery has been replaced the remote locking is still not working.  One reason is that if the battery has been flat for a while your car may not recognise the key fob's remote signal any longer and it will need to be reset.

The bad news is that your Ford dealer will charge anything up to £50 to re-programme the key; the good news is that you should be able to do it yourself.

NB.  This worked for my 2002 Ford Focus (UK) with a Radio Frequency (RF) key fob - it may not work for other models so try it at your own risk!

It's very simple to reset the key fob code:

1)  Insert your key into the ignition and turn it to the first position (I).
2)  Rapidly turn the key from Position I to Position II and back again (you'll need to do this 4-5 times in less than 5 seconds)
3)  You'll hear a chime similar to the "lights on" warning sound.
4)  When you hear the chime press and hold one of the key fob buttons: keep holding it down until you hear the chime sound again.
5)  Turn off the ignition and remove the key: you'll need to wait for approx 10 seconds but your remote locking should now work.

As noted before this worked a treat for my car and saved me at least £50 in dealer fees, but the process for later models especially may be slightly different.

If you'd like to see a video of how to change the key I'd recommend this one from YouTube:

(It looks like this video has now been made private)

And there's a useful discussion thread at DIYnot.com which also lists some other possible causes of Ford Focus central locking problems..