Hey thanks to you all,
I swapped the sensor with the other engine, no difference, same problem port side.
Two weeks ago I had to install a new water maker and while the boat was haul and block, we went ahead and cleaned metals again, sanded the props and left them shining.
Incredibly, it took care of the problem, no more alarms on the port engine.
Itís amazing how sensitive these sensors could be, the props where clean but not polished.
Since you guys reinforced my primary thought, I went ahead and ordered new sensors, even further, ordered one for each engine, you know, if one goes bad the other engine will too.
How smart I am !!, I now have two spare sensors, didnít use anyÖ.
Thanks to you all, and have fun, keep boating !!!!!!