First step: get a new key

You need to get a new key cut first.

The first thing you need to know is that there is a code for the shape of the key blade. This was supplied with the car from new.

Don't know what it is? There are a few options:

1. Take a picture of your key and submit it online to your supplier.
2. Request the code from your Fiat dealer (at cost), and submit it online to your supplier.
3. Take the existing key somewhere (e.g. Timpsons) and have them cut a key to match

I couldn't find my code quickly, so I took a picture and submitted it to (I have no connection to them, they just fitted the bill)

Then I received in the post:

1. The code
2. A key

The key mechanically fits the door/boot/ignition, but will not start the car because it doesn't contain the immobiliser transponder, so the engine doesn't fire up (although it does turn over).

Second step: remove the transponder chip from the old worn out key

Here is a good way of doing it


Using a super sharp razor blade scraper, I carefully cut all the way around the soft rubber over moulding. Go slowly, lots of shallow cuts are a neat and safer way to do the job.

Then I was able to separate the over moulding from the key body:


Note the location of the transponder. If you went at it hard with the blade, you could break the transponder itself, which is a delicate glass capsule.

The soft blue rubber is an overmoulding. The reason the chip doesn't rattle about in its pocket is that some of the rubber has bonded it in place during the overmoulding process. Be careful when removing the overmoulding, there is a sprue around the transponder.

Once the overmoulding is off, gently tap the key and the transponder will fall out. Drop it onto something soft!

Step 3: Put it in your new key

Here's the old and new side by side:


And here's the inside of the new key, complete with moulded in pocket for the chip:


Pop the chip in. You could bond it in to stop it rattling about (superglue) if you are brave. I used a tiny bit of blue tac to stop it moving.

I then snapped the key shut, taking care not to disturb the transponder. If you make a mistake, use the same razor blade scraper to gently prise the two halves apart.

Step 4: test

Fire your car up. Enjoy a moment of turning the ignition on without any jiggling of keys.

You can retain the old key, it's useful for those moments when you accidentally lock your new key in the boot;)