IBC light Iveco Eurocargo?

Hello, looking for some help with my 2003 Iveco Eurocargo. The IBC light is showing which u understand to be no communication between the oil pressure switch and tach. I have disconnected the battery to try and reset the fault however it is still showing when I reconnect them. Any ideas on what to try next? I also had an EDC fault so changed the fuel pressure sensor and fuel teperature sensor, the lorry turns over for ages and will half fire up a couple of times, the one time it started it ran but qould only rev just into the green. Any help would be much appreciated as I'm not sure where to try next and if the IBC fauot is my problem or something deeper...

Many thanks,

Sam