We've just recently experience the same alarm. First, you can stop the alarm and clear the error message by hitting the check and X buttons on the upper right of the display. We checked with the factory and determined it was not a critical function so we continued our day cruise, canceling the alarm each time it came on. All gauges and performance appeared normal.
We set out again, a few days ago, but first had our service mechanic check to confirm there was no risk to us or the boat. He traced the alarm to the wire harness, very near the fuel pump (you know, the one you used to have to prime is you had a cold-start problem). He could make the alarm go off (and the display clear the error message) by jiggling the wiring. He suspects it may be a wiring problem, and not necessarily a failing sensor.
So, off we went. The alarm eventually returned. After clearing it a few times it stopped. Same on our return trip yesterday. Our mechanic said removing and replacing the harness required a special Cummins tool. Haven't confirmed this yet.
Cheers,
Bruce