Hyundai trajet trouble

[sapper]

Does anyone know how to change the engine speed input solenoid on a Trajet. A chap at work has one and it can drive for week without problem then starts to play up for no reason. The fault code reader at a local indie tells that the engine speed input solenoid is not reading correctly. Said indie is not willing to work on the car and sugests going to a dealer. Could it be something as simple as a loose connection.
Thanks in advance

[sapper]

Cheers chaps. if it is the crank sensor is it an easy fix??