Yamaha 200HP 2 stroke alarm went off

Hi, Was running my 200HP 2 stroke at around 4200rpm when the alarm went off. Immediately stopped the engine and checked oil level, both tanks were full. Digital tach gauge showed no problem. Water was coming out of the "pee" hole and engine did not appear to be over heated. 5 minutes later turned key, engine fired straight up, no alarm. Motored back to marina, approx 30 minutes, 4000 rpm, no alarms, no apparent problems. Has anyone got any idea why the alarm went off, or what I should check. my thoughts would be a faulty sensor??? Thanks in advance, David

I have a similar problem, if I stay above 4000RPM alarm comes on, after awhile goes off when engine is switched off, if I stay below 4000 its ok. I have noticed that the "pee" water discharge is slightly less on this engine. Wondering if there was any solution or where to start?

it is either bad battery connections or cables

The water jacket may have salt build up. This was the same problem I had on my 115 HP. I cleaned the water jackets and no more problems.

Thanks for the replies. Problem now solved. Had a Yamaha dealer check it out, should have done that the first time. Turns out the mechaninic that did my last service replaced everything he said he did but used Mercury thermostats instead of the Yamaha ones. They are smaller diameter and were restricting the water flow at high RPM's. Temperature gun now proves all is good.