Dishwasher overfills with water, may leak from door, and displays E4.

Safety first: Turn off power at the breaker and shut off the water supply immediately if overfilling occurs.

• Inspect float assembly: Open the door and locate the float in the tub bottom. Remove any debris, detergent buildup, or utensils that may be preventing it from moving freely. Lift and drop it several times to ensure smooth motion.
• Test float switch: Access the float switch from beneath the tub. Disconnect power, remove the wires, and test continuity with a multimeter while manually raising and lowering the float. The switch should open and close distinctly. Replace if stuck closed or intermittent.
• Check water inlet valve: With water supply off and power disconnected, remove the inlet valve. Inspect for mineral buildup or mechanical sticking. If water continues to flow into the tub when the machine is off and supply is on, the valve is stuck open and must be replaced.
• Inspect wiring and control: If float and valve test good, inspect wiring harness between float switch, valve, and control board for shorts. A failed control board that continuously energizes the valve may require professional replacement.
• Dry out base pan: If the base pan has an overflow float or leak sensor, sponge out any water before reassembly to clear the error.