These LG models are notorious for the relay board going bad and causing this problem. What happens is the heat relay on the board sticks either ON or OFF at times and will throw your temperatures off, or won't heat at all.
The have been killing me. First part looked right, matched mine exact but was someone's damage part missing connections and was obviously meant for garbage.
Part I received Friday was brand new, wrapped in plastic but had additional plugs, ports had different numbers etc. Called gal said it shows to be correct, its not. Kept hounding for part number on mine and the numbers I gave don't match anything but the first broken piece I got had the same numbers as mine.
Need some help here. Simple to change just not getting the part.