I have a Mercruiser 4.3 and Bravo III Drive. My Buzzer Alarm for water temp, oil prs and low drive oil have been going on and off. I have replace the drive oil container so I know its not the drive. My oil prs is (25) psi at idle and my water temp is (170) when running so the alarm has no reason to come on. Has anyone gone thru this and what to check.

Is that what your manual says for water temp? I have a 142*(?) thermostat on mine 502. 170 sounds high but not sure.

The alarm buzzer uses separate senders for its warning signals. Doesn't use the same ones that the gauges use.

You may indeed have a bad sender on one of the signals.