Originally Posted by
GVK.
There's some earth terminals under the airbox on mk1 Focus and they can corrode and go green, have a look at those.
ECU update won't help this kind of fault.
If PATS fault you'd have the PATS light flashing rapidly when you're trying to crank it.
I have told her to look at the PATS LED if it happens again and note the code it flashes out.
She didnt know to look at it before, but from the description she gave me it sounds right from what I have read online.
Not sure why it would be so intermittent though?
As for the earth terminals, I did have a quick look today without taking the airbox out etc, and could see one at least, and one mounted to the side of the battery box - both did look a bit green or corroded - I did a quick spray of WD40 until i can get to them properly to have a go at cleaning them
What would you say is the best way to clean them?