Re: 2003 Evinrude 150 warning horn
If it were an overheat, the HOT lite would illuminate and the motor would slow down to 1200 rpm to minimize any internal damage.<br /><br />You did not mention any warning lites, but they are REQUIRED for that motor.<br /><br />If the CHECK ENGINE lite comes on when the horn sounds, then it could be something as simple as water in the engine's fuel filter or an internal electrical problem. A loose battery cable or too small a battery can do the same thing. A dealer can hook up his laptop and it will tell him what error code was saved.