Engine alarm will not shut off

[debtfinder]

1995 Silverton. Twin 5.7 Mercruisers with Alpha-1 drives. Starboard engine alarm engine will not shut off. According to the manual the engine alarm is triggered by low oil pressure or high engine temperature. According to my guages the engine temp is at 150 degrees and the oil pressure is 40 psi. Can this be a false alarm and if so how can I reset it? If it is not false what else could be causing it?