Amana Dishwasher Error Code 6-4

Code 6-4 means the control board is detecting an open float switch, which is the overfill protection switch inside the tub. The machine interprets this as a signal that water has reached the maximum safe level. Possible causes include a stuck float, an unlevel dishwasher, a leaking drain check valve allowing backflow, a stuck-open fill valve, or a shorted triac on the control board.

Running the dishwasher with an active 6-4 code is not recommended. If the cause is a stuck-open fill valve or a failed check valve allowing backflow, continuing to run cycles risks water overflowing onto the floor and causing water damage. The machine may also shut down mid-cycle. Diagnose and clear the root cause before running a full wash cycle.

A recurring 6-4 code after clearing means the underlying cause has not been resolved. If the float and levelness check out fine, the next step is to look for standing water in the tub after a drain cycle, which would point to a failing drain check valve allowing backflow. If water is actively entering the tub when the machine is not filling, the fill valve is mechanically stuck open or the control board's fill valve triac has shorted and is sending power to the valve continuously.

Start by removing the bottom rack and inspecting the float, which is the small plastic cap near the front corner of the tub floor. Remove anything lodged under it, press it down and release it, and listen for a click from the switch below. Then check that all four leveling legs are adjusted so the machine sits flat on the floor. If the float moves freely and the unit is level but the code returns, inspect the drain hose check valve for backflow and test the fill valve for mechanical failure. A shorted fill valve triac on the control board is the least common cause but requires board replacement if confirmed.

If the fix is simply clearing debris from the float or adjusting the leveling legs, there is no parts cost. A replacement drain check valve is typically a low-cost part, often under $20. A new fill valve runs roughly $20 to $50 in parts. A replacement control board is the most expensive repair, commonly ranging from $80 to $200 or more for parts alone, plus labor if you hire a technician. Diagnosing which component is at fault before ordering parts will save money.