Iveco 35c14hp 2006 year?

Driving home and vehicle cuts out, dash board starts flashing ingecter and yellow half full bottle sign.was told to change fuel filter,did that but wont start or fire up.A friend has a code reader which cumes up with 2a fuel preheat relay fault. What and where is it, and would that make it not start.

Christopher Leach
February 2013