What can cause this consistently at 3800 on 525. Thanks

you should have a switch on the shift plate, its the in-gear switch. The switch is telling the ECM that its in neutral. Unplug the switch and it will go away. Unplugging it hurts nothing, but your idle might change by 50 rpms

I’ll give that a try thanks! But on my vessel view it shows that the motor is in gear when put into gear. Put it in neutral it shows in neutral.

I've read a failing crank sensor will also trigger the overspeed fault.

Issue was fixed with replacing the gear selector switch that was suggested to unplug. Thank you!