Why has my Ford Focus' speedometer has developed an intermittent fault?

I have a Ford Focus estate with a 1.8 Zetec engine, registered in 2001. It has now travelled about 75,000 miles with no problems. Recently a fault has developed: the speedo and milometer stopped working intermittently. All the other dials remain working, so I have to judge my speed from the rev counter. The speedo stops working for 5-10 minutes then starts up again of its own accord, there is no pattern to this failure. If I am on the motorway or driving along I can feel a slight loss of power when this happens, and a slight increase when it recovers. The dangerous bit is if I am crawling along in traffic, or changing gear when the meter is dead as the engine cuts out and I lose my power assisted brakes and steering. I have looked on the Internet and this fault in various forms seems common on older Fords, and a number of models but no single cure is given.

Asked on 3 March 2012 by LP, London N6

Answered by Honest John
Hopefully, quite a simple fix. It's usually caused by failure of the oil gasket to the speed sensor in the final drive. The repair costs about £100. The reason for the other problems is can-bus electrics. When one component on the power supply fails, this can affect others on the same power supply.
Similar questions
My Ford Focus 1.6 has done 88,000 miles. It kept showing an intermittent display fault with the odometer, speedometer, fuel gauge and temperature gauge all not working. Now none of these have worked at...
During a recent service on my 2010 Hyundai i30, the dealer told me that the digital instrument binnacle display was flickering and needed to be replaced under warranty. I was happy for the work to be done,...
I'm getting erroneous low oil pressure warnings in my P-reg Volkswagen Polo and the rev counter and speedo are not working. Also a beep is sounding occasionally. Oil contents ok, all lights seem to be...
 

Value my car

Save £75 on Warranty using code HJ75

with MotorEasy

Get a warranty quote

Save 12% on GAP Insurance

Use HJ21 to save on an ALA policy

See offer