MTU coolant pressure alarm

Swap port to starboard?

How old are your batteries. If 2.5 years old or older, replace. Check your batteries for any AC voltage leaking from the charger. Call an MTU dealer.

Could be a leaky cap seal .Use a bit of cling film or equivalent under the cap to re seal it .If the alarm stops then you know = new cap(s)

I remember my dad telling me that if water gets into the coolant system, it will register the same pressure at a lower volume so that could confuse sensors a little bit too.

All the previous comments are valid. Let me throw one more possibility out there; restriction. Has the system been flushed?

I'd recommend contacting Charleston City Marina for a recommendation. They found us one several years back and he worked out well. Don't remember his name, but I believe he came down from near Hilton Head.

there is a good man dealer near there. I’ve used them. Their rates are reasonable compared to south florida standards. Do you have mans or mtu? They’re located in that inlet between Hilton head and Charleston. I forget their name but they go to both places. When I’ve had multiple erroneous alarms with common rails it turned out that the engine batteries were going bad and voltage dropped too much when cranking and set off the alarms.

Sensors do go bad on MAN's. Depends on the era of the MAN's.......but expect to change 1 sensor (between the 2 motors) every 1-2 years. They've gotten to be a lot better (the replacements). Also sometimes the 1 sensor that goes bad causes the display to say it's a different sensor. Old engine batteries will also definately do this with MAN's. If you get multiple sensor alarms on start up, it's engine batteries. Voltage drops too low after firing and causes the computer to do funny things and it'll have 4 sensor alarms. There is a MAN dealer in Wadmalaw inlet I think I used and they were pretty reasonable and came up to Charleston first thing the next morning.....really knowledgable tech......about 7 years ago and their rate was what independent mechanics charged here in Fort Laud. Although Savannah would probably/maybe be closer.

Diesel Engine Service | marinepropulsion (marinepropulsionsc.com)