Increase water level in a bosh washer - Bosch Nexxt Premium WFMC6400UC Front Load Washer

It's underfilling The water-level switch regulates your washer's fill volume. This switch is usually a diaphragm device with a small, clear tube attached between the switch and the bottom of the washer's outer tub. As the water level in the tub increases, the pressure on the air in the tube increases. When the pressure reaches a certain level, it activates the switch, shuts off the water, and signals the timer to begin the agitate cycle. If the switch is defective, it may prematurely signal the water to shut off. If so, you probably need to replace the water-level switch.

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The water-level switch regulates your washer's fill volume. This switch is usually a diaphragm device with a small, clear tube attached between the switch and the bottom of the washer's outer tub. As the water level in the tub increases, the pressure on the air in the tube increases. When the pressure reaches a certain level, it activates the switch, shuts off the water, and signals the timer to begin the agitate cycle. If the switch is defective, it may prematurely signal the water to shut off. If so, you probably need to replace the water-level switch.

The water-level switch regulates your washer's fill volume. This switch is usually a diaphragm device with a small, clear tube attached between the switch and the bottom of the washer's outer tub. As the water level in the tub increases, the pressure on the air in the tube increases. When the pressure reaches a certain level, it activates the switch, shuts off the water, and signals the timer to begin the agitate cycle. If the switch is defective, it may prematurely signal the water to shut off. If so, you probably need to replace the water-level switch.

The water-level switch regulates your washer's fill volume. This switch is usually a diaphragm device with a small, clear tube attached between the switch and the bottom of the washer's outer tub. As the water level in the tub increases, the pressure on the air in the tube increases. When the pressure reaches a certain level, it activates the switch, shuts off the water, and signals the timer to begin the agitate cycle. If the switch is defective, it may prematurely signal the water to shut off. If so, you probably need to replace the water-level switch.

The water-level switch regulates your washer's fill volume. This switch is usually a diaphragm device with a small, clear tube attached between the switch and the bottom of the washer's outer tub. As the water level in the tub increases, the pressure on the air in the tube increases. When the pressure reaches a certain level, it activates the switch, shuts off the water, and signals the timer to begin the agitate cycle. If the switch is defective, it may prematurely signal the water to shut off. If so, you probably need to replace the water-level switch.

Remove hose at washer connection and check screen filter not blocked with grit from pipes. Check screen at tap end also. If both clear, machine may need water valve replaced.

It's underfilling The water-level switch regulates your washer's fill volume. This switch is usually a diaphragm device with a small, clear tube attached between the switch and the bottom of the washer's outer tub. As the water level in the tub increases, the pressure on the air in the tube increases. When the pressure reaches a certain level, it activates the switch, shuts off the water, and signals the timer to begin the agitate cycle. If the switch is defective, it may prematurely signal the water to shut off. If so, you probably need to replace the water-level switch.

It's overfilling If your washer is overfilling, check these:

Water-inlet valve
Water-level switch
Water-inlet valve A defect in the water-inlet valve may mean that it's no longer able to shut off completely when the electricity has been turned off to it. If this occurs, the valve may leak and drip water into the clothes tub. In time, the water may accumulate substantially. If this happens, you need to replace the valve.

Water-level switch A defect--or an obstruction--in the water-level switch may mean that it can't tell the water to shut off. So the machine overflows. This switch senses the water level in the clothes tub. It's usually a diaphragm device with a small, clear tube attached between the switch and the bottom of the washer's outer tub. As the water level in the tub increases, the pressure on the air in the tube increases. When the pressure reaches a certain level, it activates the switch, shuts off the water, and signals the timer to begin the agitate cycle. You can either clear any obstruction in the tube or replace the water-level switch.

It's underfilling The water-level switch regulates your washer's fill volume. This switch is usually a diaphragm device with a small, clear tube attached between the switch and the bottom of the washer's outer tub. As the water level in the tub increases, the pressure on the air in the tube increases. When the pressure reaches a certain level, it activates the switch, shuts off the water, and signals the timer to begin the agitate cycle. If the switch is defective, it may prematurely signal the water to shut off. If so, you probably need to replace the water-level switch.

The water temperature is incorrect The temperature of the incoming water determines the temperature of the water in your washer. You get either hot, cold, or a mix of the hot and cold water that's currently available to the machine. So if the cold water that enters the machine is very cold--or if the hot water entering the machine is very hot--the warm water is affected. 

If you live in a Northern climate, unless you adjust the hot and cold water taps that supply water to your washer, the warm water supplied to your washer is usually hotter during the summer months and colder during the winter months.

Hi,
I found this answer on Repairclinic.com. Hope it helps...

Water-level switch A defect--or an obstruction--in the water-level switch may mean that it can't tell the water to shut off. So the machine overflows. This switch senses the water level in the clothes tub. It's usually a diaphragm device with a small, clear tube attached between the switch and the bottom of the washer's outer tub. As the water level in the tub increases, the pressure on the air in the tube increases. When the pressure reaches a certain level, it activates the switch, shuts off the water, and signals the timer to begin the agitate cycle. You can either clear any obstruction in the tube or replace the water-level switch.

NO you cannot increase the water it is designed to use a low amount of water which is why it is considered an energy effecient washer