Joe I have same problem on a 2007 Primastar. Just had it on diagnostics at Nissan. ( £81.60) No one else has the software to identify the problem. They tell me combi unit has failed. Presumably this is some sort circuit board that collects information from the various senders and turns it into a digital readout. Quoted me £480 for part.
Alan Peet, June 2011
could be you sender unit has failed, might need to change it, get one cheap from good scrappy.