My 13 year old Kenmore 665 dishwasher overfills. I have checked the overfill control valve, but it's OK. No matter what I do, water keeps flowing into the machine from the intake port on the left side. What do I do?

More than likely the water fill valve is bad and needs replaced

Esquire's is likely correct but tell us how you checked that overflow valve and know it is OK. It is actually a float switch that interrupts the power to the fill solenoid.

Esquire's is likely correct but tell us how you checked that overflow valve and know it is OK. It is actually a float switch that interrupts the power to the fill solenoid.
I took the switch out and checked it with my VOM