Yamaha Ox66 False Warning Horn

[fgunnr]

I have a 1997 225hp OX66. The warning horn will sound and the engine will slow down indicating an overheating situation. But the engine is not overheating(engine temp is normal to the touch with the cowl removed and the water from the engine is normal temp). This happens every time I go out and will last for about 15 minutes and then everything is normal. Sometimes I can run for 45 minutes between warning horn sessions. The engine has 340 hours on it.

I have talked to one dealer and he is suggesting changing the sensor.

Is ther anything else I should check?

thanks