Product review (3 stars): I had an HE error on a LG LDS5540ST,  I don't think this was the problem.
Don't buy this dishwasher.  It does clean decently but has failed multiple times in less then two years.

Update:  if you get HE error, pull out the dishwasher and check the left side where several tubes are located.  There is a clear box that has two floats in it, there are electrical wires connected to switches that can be triggered by the floats.  The problem is, gunk gets built up on the floats and in the clear box that holds the floats.  If the floats can't function, the water will not feel up correctly in the tub, overheating the heating element, resulting in an HE error.  Once you clear it out and reconnect, no more HE error!