I have a Ford Focus and every so often the speedometer goes dead while driving, what could be the cause.?

I don't know what year the Focus is but, the speedo signal is picked up from a speed signal sensor on the trans. Should this sensor be faulty it will cause the speedo not to work and also the ECU (engine control unit) will not have a signal to work out what speed the vehicle is travelling at versus engine speed etc.

I hope this gives you somewhere to start at..

yeah, its not timing, its a speed signal problem. But with a focus, this signal bounces around from engine computer to instrument cluster and even to the radio in some of the newer ones (03 and up). Could be wiring going to any of these, but most commonly, it is just the sensor. Its located on the tranny, but its hard to see becuase its fairly well covered up by everything else in the engine bay. You may need to have a professional to make sure ya get the right one... it is very similar looking to the oss and iss sensors on the tranny, and you want to make sure to replace the right one.

i dont know if u will understand me but u need to have some one check your timings for the car the timings can sometimes go out of place(its not actual time like a clock)when this happens the car will jerk when it reaches certain speed and even some times when pulling off and even giving u probs to start eventually ,as for the speedometer it could be that the speedometer cable is worn out its a round cable thats spins as fast as u go inorder to make the needle in the clock move u might need to replace it.take it the the shop and have them service the car.

what variety of song-up did you get that the technician didnt' examine the computing device's clarification for turning on the engine mild? may well be various issues; can not tell from the reasonable description given.

The cause is that you bought a piece-of-shi t car. You have to feed the four gerbils that control the speed in order to fix that problem.