Hi all. 

I have a 2006 Fiesta. So recently the car wouldn’t start. Had AA out. Said battery was fine but needed a jump start. Same issue again a few days later, tried bump starting it. No luck. AA came out. Wouldn’t start this time. Now the car isn’t even turning over. The immobiliser light is staying on and the engine doesn’t even try to turn over. AA went through all the fuses and relays and no issues found. The key was turning the engine over initially now there’s nothing. Just the immobiliser light staying on. Can anyone help? Thanks in advance. 

Read Here...sounds like a key problem or the ring(if it has one) that goes around the ignition barrel not picking up key pairing.

 

https://thecarkeyman.co.uk/key-news/ford-car-key-problem/

when my brother's focus was behaving like this it was a big electrical connector plug under the bonnet which had dodgy contacts in it. I have no idea where such connectors might be on the fiesta. The ECU needs to detect the key. If you can find where the ECU is then maybe check all connectors that might be between there and the ignition lock. 

Breakdown service man said it needed the key reprogramming to the ECU but he was wrong. It was electrical connection fault between key code reader (by the ignition lock) and the ECU which was under the left hand front wing.(I think from memory it was the Canbus wires - I do not know if fiesta uses canbus in same way as focus)