I have a 42 tiger with twin 575 SCI Mercruiser motors, the Port side motor alarm started out intermittent then lately is staying on the whole time, both oil pressure and water temperature are perfect on the gauges, thinking bad sensor, any thoughts from anyone?

The alarm sensors are separate from the guage sensors. The alarm sensors use a tan with blue stripe wire.
I think the only things that trigger an alarm on a 575sci are low oil psi, high water temp and low drive lube.

Disconnect one sensor at time to find the bad one. Also, check the drive lube bottle for sludge at the bottom preventing the sensor from working properly.