Sounds like an immobiliser fault, likely to be caused by bad soldering in the dash cluster (speedo clocks), fairly common issue on the Mk2 although less frequent on the Mk2.5. If you have a Windows laptop I'd recommend Forscan over any generic OBD scanner.
Ford Model: 1.8 TDCI Mk2 Focus Ford Year: 2006 UK/Ireland Location: Dorset I'm very surprised it hasn't produced an 'engine systems fault' on the dash though.Last night however I was driving home and as I was approaching a roundabout at 40mph in 5th gear I changed down to 3rd gear then to 2nd gear and the engine systems fault warning light came on. The car then started "juddering" and would not go above 20mph or 2000 revs. I pulled over after crawling round the roundabout and turned the engine off.
Ford Model: Focus 1.6 tdci Ford Year: Ford Model: Mk2 Ghia 2ltr TDCI Ford Year: 2008 Ford Focus Ztec - engine issue.
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