I have found a solution 4E error for my Samsung WD7101CKW. Water that comes inside washer is splitted in splitter with valves. One of these valves has a red label on it - this is a valve with restrictor of flow inside. This restrictor is used to limit flow speed mainly for testing purposes of pressure/water level sensor. Because of that restrictor (red cap with two holes of 0,5 mm diameter) blocked flow too much, after some time washer controller thinks that water has too low pressure.
Unplug washer, disassemble hoses from valves, disassemble valves from the washer (screwdriver needed), drill both holes in red restrictor to 1 mm (use 1 mm drill or just big needle). Assemble in reverse. Will work :)
Greetings - Thomas
Thomas Pirowski, April 2008