Ford Focus MK2 PATS code 25 after changing the battery

[ddrums9]

Hi, I changed the battery on my 1.8 tdci, 2007 Focus yesterday, as it was quite old and was causing me issues with starting on cold mornings. Unfortunately the car now won't start, and the red immobiliser light is rapidly flashing and then giving me 0ne slow blink and then 6 faster blinks. I think this means it is error code 16. The car was fine, other than the old battery before this.

Does anyone have any ideas what that code is telling me or what the problem may be, please? Nightmare.

Many thanks in advance.

[Maelstrom666]

New, charged battery?

Code 16 is the ECM being unable to get the transponder code from the chip in your key (via the PATS immobiliser).

How you triggered that I don't know. I'd try disconnecting the battery, making sure it is charged and connected properly via clean terminals, getting the alarm to arm etc, see if there is a key fob registration procedure you can follow.