The LG WashCombo washes and dries in one drum with no vent to the outside. Instead of blowing hot air out of the house, it runs a heat pump: warm air passes through the tumbling load, picks up moisture, is cooled so the moisture condenses, and is reheated to go round again. The condensate leaves through the same drain hose the wash water uses. dHE is the code LG assigns to a problem during that drying phase, and because the heat pump is sealed and unfamiliar, owners tend to assume the worst. LG's own dHE article starts with much simpler things.
What dHE Is Reporting
The control expected the air temperature or the moisture level to move in a certain way during drying and it did not. Anything that stops air moving through the load, or stops condensate leaving the machine, can produce that result. The heat pump itself is the last item on the list, not the first.
Check the Lint Filter First
The combo collects lint in a filter that is reached without tools; its position is shown in the manual for your model. Wait for the drum and door area to cool after a drying cycle before you reach in, because the air path is warm. Remove the filter, clear it completely, rinse it if the manual allows and let it dry, then refit it until it clicks. A filter that is partly blocked does not stop the machine, it slows the airflow until the control gives up and shows dHE. Clean it every load, the way you would a dryer's screen.
Then the Load
A WashCombo washes more than it can dry in one go; the drying capacity is lower than the wash capacity, and the manual gives both. A drum packed for a full wash and then sent straight into drying has no room for air to pass through the load. Reduce the load, or wash full and split the drying into two runs. Very heavy items such as a comforter behave the same way even in a small load.
Then the Drain
Condensate from drying is pumped out through the drain hose, so a drain that is marginal in the wash phase can be the reason drying fails. Look at the visible drain hose for a kink, and check that its end sits at the height the installation instructions give and is not pushed deep into the standpipe. If the machine has shown OE at any point, the drain pump filter needs clearing: with the WashCombo unplugged, the drum cool and a shallow pan on the floor, open the small door at the bottom front, let the water out through the drain hose stub, then unscrew the filter and clear it.
Room Conditions
A heat pump exchanges heat with the room. LG specifies an ambient temperature range for the machine, and a very cold garage or a closet with the door shut and no air movement can push the cycle outside it. If dHE only appears in winter or only when the laundry door is closed, that is a strong hint.
What Is Left Is Technician Work
If the filter is clean, the load is right, the drain is clear and the room is normal, dHE points at the heat pump circuit, its thermistors or the drying fan. The compressor and refrigerant are a sealed system that only certified people may open, and the fan and sensors sit inside the cabinet with mains wiring. Do not remove panels to look. Note whether the machine still washes normally, whether the drying phase produced any warmth at all, and how long it ran before the code appeared, and book an LG WashCombo repair with the model number from the plate inside the door.