410 Sundancer 7.4 Diagnostic alarm

My 2000 410 Sundancer 7.4 Mercruiser Starboard engine diagnostic alarm goes off when gets on plane. I had engine diagnostics performed on engine and no faults or recording of problem recorded. The mechanic has put various new sensors on and still alarm goes off. They want to switch ECM from port to stbd. Any ideas? By the way boat runs fine during this.
Thanks for any input before I spend more $.

I have a 2000 Sea Ray 340 dancer with Mercruiser 454 7.4 MPI that also recently started the engine alarm on Port engine after getting on plane for a few minutes. The alarm patten which repeats is 1 beep - 3 seconds no beep - 1 beep. When I shut off the engine and start again, the alarm goes off. But will come back if I cruise above 3000 RPM for 5-10 mins.

Anyone have information on what this alarm code means? The boat seems to run fine and oil temp and pressure is normal.

Thanks

Exactly same as mine. They are going to switch ECM this week, will let you know if works. If any ideas please let me know. Thanks.