Hello, we have a 26' Maxum that beeps at low idle, all fluids are good, what else could it be?

One of the sensors could be faulty or something as simple as a wire
coming off the sensor terminal.

I checked all harnesses and terminations, wiring looks good, how do i locate sensor/sensors? Where is the sensor harness for a 2006 Maxum Bravo Three, cant find it in owners manual? Thank you for your reply