Guide: Replacing the car key body / key fob (Mondeo mk5 / Fusion / Mustang)

If your key fob is starting to look old and worn, it’s fairly easy to swap the gadgetry inside over to a brand new key body. I made a video, below, that shows the process and a text summary of the steps involved can be found below it, as well as a link to the key fob that I bought from Aliexpress.

You will need:

  • A small plastic prying tool or screwdriver
  • A new key body ordered from aliexpress


It’s quite easy – since all the electronics and transceiver in the Ford Mondeo mk5 (Fusion) key body is all integrated into the circuit board, re-bodying the key is a non-destructive process and keeps the old key body intact.

I have previously done this with the key fob for my Wife’s 2014 Kia Cee’d – that involved using a soldering iron to melt the plastic body of the key in order to remove the transponder chip that is superglued inside of it, Thankfully this time it would be much easier!

So, to get started:

  1. Open the key by pressing down on the switch on the back of the key fob
  2. Remove the physical key
  3. Pry off the battery compartment (3 clips on either side and one at the top)
  4. Remove the batteries, battery separator and electrical contacts from the battery compartment
  5. Insert the batteries (positive sides facing together, separated by the plastic battery separator) and the relevant electrical contacts in to the new keys battery compartment
  6. Remove the circuit board from the old key and take off the old pink dust cover
  7. Place the circuit board into the new pink silicone dust cover.
  8. Insert the circuit board and silicone cover into the front cover of the new key
  9. Move over any soft protective pads that aren’t present on the new key body from the old key
  10. Reassemble and test!

Questions or comments? Let me know!