DCS DD224P5 2-Drawer Faulting "Heavy"-"Rinse" U01?

3 year old DCS (Fisher Paykel) 2-drawer dishwasher. Model: DD224P5. Top drawer will start a wash cycle to eventually error out. Lights "Heavy" & "Rinse" are light on panel inside drawer. Pressing Power button clears it, Middle Start button flashes blue and blue with a red outer band. Hitting start the drawer will start washing. It will eventually error out again. I took the basket out to remove the spray arm, the stainless plate, and the rotor that spins the spray arm. Found and cleaned extra soap from all three. Rotor spins freely along with arm.
Where would I start looking to narrow down the "U01"/"Fill Fault" error. Can't find any information on troubleshooting this problem.

Thanks,
Ray