Ph1 306 Xsi Speedometer Fault?

[Colactix]

Right, I'm in a bit of a predicament. Got my driving test on Friday, and I really don't want to cancel it - with Covid I've been waiting since March, and not being able to drive is sickening me. 

My speedometer is intermittent, it's been this way since I got the car about 10 months ago. For the past 2 months it's been working absolutely fine, but it decided to take a dive at the very worst moment this week. Sometimes it works, sometimes it doesn't. It'll flick around and then work for the next mile, die, repeat. 

I've replaced the speed sensor, and the plug on it looks fine.
I took the instrument panel out today and everything behind there looks fine too. 

I'm stumped, could it be the dial, or the panel itself, the loom wires? The fact that it seems to work at random points puzzles me.

Any ideas?

[Mighty306]

Is the wiring all the way to the speed sensor good? Intermittent short to ground maybe?

[Colactix]

Is the wiring all the way to the speed sensor good? Intermittent short to ground maybe?

I couldn't see any obvious damage on the wire, but I'll check again tomorrow, thanks!

[ekjdm14]

If all else fails, could you get a GPS speedometer app on your phone & have that in a phone holder on the dash? (obviously visible, but not obscuring your view, probably one of the vent-mounted holders ideal)

EDIT just realised I'm a week late to the party sorry, hope you managed to get your test passed OK? I remember an old mate was taking the test in his Fiesta 1.8D van conversion & on the emergency stop the brakes jammed on due to a failing flexi hose, happy he was not!