Hello

I have a fiesta mk6 1.4 petrol . Had an electrical fault where it wouldn't start. Dash would glow and it would say high engine temperature even when the engine is cold. I did some searching and found that there was a small blue wire stemming off of  the negative terminal which was loose, I tightened it up and the engine started absolutely. Does anybody know what that little blue wire would be .? many thanks.

Looks rather aftermarket...

Possibly an immobiliser fitted by a finance company for example so if the payments are defaulted then they can remotely stop the car from being started. A similar device may have been fitted by the actual owner of the car incase it was stolen.

Only a guess, you'll have to go routing behind the dash and see what you find.

Thanks for replying . Yeah basically if I loosen the wire, the car will immobilise saying high engine temp which is strange I guess and not start, and then when I tighten it again , it's fine. It's happened a few times since I've owned it haha and only just seen this wire was loose. I was convinced it was ecu but it's not, fingers crossed haha . I know now when diagnosing a problem to start with the simple things haha

 

It's a 2008 fiesta mk6.5