When a LG front loading washer displays an IE error code, it refers to water input failure. Most online diagnostics only go so far, check the filter imbedded where the hose connects to the back of the washer and then the Cold Water Inlet Valve (LG Part Number AP4445613) and the Hot water Inlet Valve, (LG Part Number AP4441935). Nothing I found online pointed to the Dispenser Assembly, LG Part Number AP4439384.
It is very easy to see if the Dispenser Assembly is the point of failure, with the water on and the machine running, attempt to squeeze the right most hose, (Hose Inlet, LG Part Number AP4998828) as you are facing the machine, connected to the assembly. This is the hose with the largest diameter. You will notice if the Dispenser Assembly is failing this hose will be very hard compared to the other three hoses.
The hardness of this hose is caused by no water being able to pass through to the assembly, due to the assembly being clogged up with lime deposit or other debris. If you have extremely hard water this most likely is your problem.