what causes an overheat alarm when the engine is not overheating

[sullmate]

Yamaha -2006- 150 hp 4 stroke. (850hours). Engine starts fine, pee hole shows a steady stream. Water pump impeller is less that two years old. When engine hits around 3800 rpm. the Alarm sounds ( steady beep). Stop, walt 15 seconds restart the engine, runs fine, no overheat signal the rest of the trip. Thoughts? Is there a sensor that could be going???

 

[saltchuckmatt]

Yamaha -2006- 150 hp 4 stroke. (850hours). Engine starts fine, pee hole shows a steady stream. Water pump impeller is less that two years old. When engine hits around 3800 rpm. the Alarm sounds ( steady beep). Stop, walt 15 seconds restart the engine, runs fine, no overheat signal the rest of the trip. Thoughts? Is there a sensor that could be going???

Probably should check top of the head with a heat gun when it happens to be sure but yes there are sensors that go bad. They are located on the back of the head.

 

[99yam40]

pulling and testing the sensors, and measuring the temps at the sensors location might give you a clue if there is an overheat condition or not