The 3 most common part(s) or condition(s) which contribute to the symptom Washer overflowing are listed below:
Water Inlet Valve
If the washer is overflowing and power is shut off to the washer, the water inlet valve has failed. Replace it.
If the washer is overflowing the pressure switch might be defective. The pressure switch is attached to a small tube which is attached to the outer wash tub. As the water level rises the air pressure in the tube increases, once the set water level is reached the pressure switch turns off power to the water inlet valve. Check to be sure the air tube to the pressure switch is clear before replacing the switch.
Low Water Pressure from House Supply
If the washer is overflowing the water pressure to the water inlet valve might be too low. The water inlet valve requires a minimum of 20 psi to shut off properly. If the pressure is lower, the valve may not close fully when the power is shut off. This results in the valve leaking water into the washer and causing it to overflow.