Ford Fiesta Starting Problem

[jason.p]

I'm tryng to help my grandson with his 56 plate Fiesta. It seems he tried to jump start it and got the polarities reversed. It will not now turn over. Battery is fully charged and all other systems seem ok. I am getting a message "engine system fault".
I would imagine something has been fried. Where would be the best place to start looking. Thanks.

[bhg481]

It sounds very much like something has been fried and there's a real danger it could be something expensive. The engine CPU is a possibility with the diagnostic you're getting but I don't see how that would stop it turning the engine. Can you try to bump start it, either with a couple of fit friends or a tow rope; if it starts it eliminates the CPU.

[Hymie]

I would think there is a fair chance that the vehicle CPU is toast.

A colleague had a Fiesta of that vintage; following using it to jump start another vehicle – he had no end of problems with the electronics, which he put down to the battery voltage dip (as a result of the jump start) scrambling the CPU.

My advice is to beg/borrow/steal/buy and OBD reader and see what it says.

Even so, it would be worth trying bhg481’s advice which might result in the CPU being reset and all being well.

[TWR]

Take the + off the battery ( Make sure you have the radio Code beforehand) leave off for 5 >>10 mins reconnect & try.

[douglas9401]

Disconnect the battery by removing the (-) negative first then the (+) positive. Leave for a while then reconnect, (+) first then (-) negative.

Try to start after that.

[jason.p]

Thanks to all for replies. I think i got away with it lightly! It was a blown fuse (3amp)- "Engine management".

[bhg481]

That's what fuses are for but, Yes, you were VERY lucky. Thanks for letting us all know.