My LG dishwashing machine model LD 2131 SH displays a F error. What does it indicate?

LG DISHWASHER ERROR CODES AND DESCRIPTION MODELS LD 1420W2 D1420WF LD...

ERROR CODES; FAULTS & REMEDY ERROR DISPLAY [IE]
Inlet error.
Condition: Not reached to the normal water level in spite of 10 min. water supply.
Possible causes:

1. The Water Tap is not opened.
2. The Inlet Hose is twisted.
3. The Filter of inlet valve clogged by impure water.
4. The Inlet Water Valve is normal ?
5. The water pressure is very low. ( below 0.5 kgf/ )
6. Inlet valve is blocked by safety device for leakage sensing.(In case of Inlet Valve).

• Open the Water Tap.
• Repair the Inlet Hose.

1. The Filter clogged.
2. The Drain Hose twistec or blocked.
3. The Drain Pump/Motor or circuit is troubled.

• Clean the Filter.
• Remove the cause of twist or block.
• Replace the Drain Pump/Motor or repair the Circuit.

1. Water leakage in Hose connections.
2. Water is leaked by damages.
3. Impeller of the washing Pump is worn away.
4. The Thermal Protector of the washing motor is functioned

• Replace the connections of Hose.
• Check the point of damages and repair or replace the related parts.
• Replace the washing pump.
• Check the applied voltage.

1. The Inlet Valve is troubled.
2. The Air Break is troubled.
3. The Sensor Assembly is troubled.
4. The Controller is troubled.

• Replace the Inlet Valve.
• Replace the air breaker.
• Replace the sensor assembly.
• Repair or replace the controller.