Speedometer sometimes it works for long periods then it will not work at all, the rev counter and km counter work fine, any ideas ???

Your rev.counter is different from your speed sensor..

abs light on ? abs controls the speedo (odometer).... dont know what you mean by clocks.... do you mean the rev counter and gauges ??

cold idle control sensor bad

vehicle speed sensor at transmission or bad wires/loose connector

Known issue with this era. Google it. Involves removing the cluster and desiring and resoldering the connections at the trace Trace connections for the speedometer and tachometer.

Its probalby the actual guage. The counter and speedometer all work off the speed snesor so if one is working and not the other its more then likely the actual guage thats bad!!

this is just a rough guess, but i think it would be the battery or the alternator. Some part store have testers that they will check both for free.

Your problem sounds as if the thermo sensor....which controls the air fuel ratio when engine is cold....is faulty. It is a common fault on this model.
This is not an expensive part, and takes only a short time to fit.
Good luck
John

sounds like the idle speed sensor,if your rpm's are idling up and down

If your transmission fluid level is okay, then you need a new speedometer cable. Its not terribly difficult to replace, but it does require you to pull the instrument cluster. A local Hyundai dealership might be willing to photocopy the specific speedometer cable replacement instructions out of the 2004 Accent shop manual.