Man V8 Engines CR900 Alarm Couple of times the expansion tank coolant pressure alarm on starboard engine has gone off. Went off again yesterday. I see no signs on the sb engine instruments that are concerning except on the expansion tank coolant pressure reading it shows no pressure. The other shows 9 psi at idle. Pretty sure it's probably the sensor but what should I check for besides coolant in tank and loose wire on sensor. No work has been performed on the engines for the past 7 months.