Onan Generator Fault Code 2- Low oil pressure

the oil pressure switch on that unit is a NC type switch, and it is "closed " to ground with no oil pressure. the switch "opens" on rising o.p., (about 7-9 psi) . The switch is indeed difficult to access without being able to remove top and side panels from set. these switches dont usually fail on an intermittent basis, but is possible. I have more problems with leaking than not working correctly. Not likely to be a problem with oil pump pick-up, as it happen on every start-up, and Kubota's quality control is very high. Possible that there is moisture/corrosion in wire harness connector to Inverter-controller, shorting out oil switch wire...I've run into this before. Would advise not to overfill oil level very much, as previous post said, that can cause oil to churn and foam in crankcase, tricking switch to close.