200 Merc. Beeping

Hello,

My engine all of a sudden starting doing this beeping thing. All of a sudden it will start this long continious beep, and the only way to make it stop is to put the throttle in neutral and just wait a minute or so.

Someone mentioned that I may need to change the impella (did I spell that correctly).

Is it an overheating warning?

Thanks

ps. the engine is a 94.