07 BF225 motor makes beep noise only at idle but not typical like others are seeing

I have read and searched threads but none similar to what I have. Now this only happens when I'm on the water, not when I'm flushing my motor with fresh water. When I'm moving in the water anything higher than 3 miles an hour, it's fine. When I'm idle in neutral, that's when it starts beeping and the red check engine light goes on. Now the motor does not shut down due to it either. Temp. is good, no over heat. Yes I have done my major routine maintenance ( motor oil, and gear oil change, spark plugs, thermostats, impeller, all factory parts. I don't have salt water build up as not only I have checked through the water passages, I also flush with water and salt away. I take really good care of my motor as it's kinda my lifeline out on the open blue. It never left me stranded or gave me any trouble, just this beep sound. The motor runs excellent and never skipped a beat. I only have this beep noise in neutral on the water. The only thing I could think of is O2 sensor. I remember getting a letter from Honda on a recall but I can't seem to find that damn paperwork and I forgot what it was for. It may have been for that O2 sensor. Does anyone have that same issue and have resolved it?

You can check for an HO2 sensor fault by shunting the red service connector as described many times on this forum. If you need instructions, send me an e-mail at [email protected]. Once the shunt is in place and you turn on the key switch, a single blink on the MIL light, repeated every 3 seconds or so, indicates a faulty HO2 sensor or faulty connection. If it is something else, then you will get different blink codes that will pinpoint the source of the problem.

My boat is at storage so as soon as I get the opportunity to get to the boat and look for that connector, I'll give it a shot. I haven't had the thought to look for the O2 sensor, where is it located? is it easily accessable? Thanks for the reply back and I'll get back to you to let you know what I've found.

It's on top of the exhaust manifold. I think it's on the port side, but forgotten exactly where. Don't have my shop manual handy.