Built April 2009
The first thing that I'd verify---is that the Drain Hose is correctly installed.
The Drain Hose should be mounted/installed at either the Sink Disposer side discharge---or to a Sink Air Gap (with the hose elevated at some point---equal to the height of the dishwasher)
On LG LDF6920 dishwashers with Serial Numbers ranging from 501Kxxx through 907Kxxx (January 2005 thru July 2009)---the cycle profile/programming---allows for partial draining of dirty wash water at times.
After partial draining---the "computer" (Main Board) will activate the Water Valve to add "clean" water into the tub during the cycle.
If the Drain Hose has been incorrectly installed too low or through the floor into a basement drain connection---water can continue to siphon/drain during the cycle.
This results in a "sucking sound" by the wash motor/alternating fast & slow motor RPMs/ poor wash performance and potentially---an "E1" error will also be displayed.
To remedy this---LG introduced a new MAIN BOARD (6871DD1006Q
) to replace the original 6871DD1006N
Main Board---which eliminates the partial drain feature.
In addition---a new DRAIN HOSE (AEM69493803
)---that has an anti-siphon break and a small black tube/hose that is to be connected to a re-designed GUIDE ASSEMBLY (4975DD1001A
)---which has a connection---for the small black anti-siphon hose.