I have the same problem - it must be that time of year! Took my 2001 4/4 Zetec for a run earlier this afternoon and all seemed Ok. Stopped for some juice and when I started up again, no odometer and then when I moved off no speedo. I've since checked that all other electrics are working fine (including the tacho) and the fuses are all OK.
I've had a problem before where the speedo was OK but the odometer display intermittently went blank. In the end it went back to the factory just under two years ago and all has been OK since then until today.
Now it is both speedo and odometer.
Before I take it back again, I'd like to be sure it is the speedo itself. My car doesn't have seat belt pretensioners so there aren't any cables under the seat and that rules out at least one of the causes discussed above. I've also checked the wiring (as far as possible) behind the dash.
My understanding is that the sensor is on the gearbox. If this was faulty, the speedo wouldn't work but that wouldn't affect the odometer display - am I right?
