ER dH means the defrost cycle ran for more than an hour without reaching its target temperature. The refrigerator is not clearing frost and ice from the evaporator area as expected — the cause can be ice accumulation, a blocked drainage hole, a failed defrost heater or sensor, or a main control board fault.
What ER dH means
LG refrigerators run periodic defrost cycles to melt frost off the evaporator coil before it restricts airflow. If the preset temperature is not reached within about an hour of that cycle running, the control board reports ER dH — the defrost process is not completing, not necessarily that a specific part has failed.
Common causes
| Cause | How likely | What to look for |
|---|---|---|
| Heavy ice accumulation on the evaporator | Common | Visible thick ice behind the freezer back panel |
| Blocked drainage hole | Common | Melted defrost water has nowhere to go and refreezes |
| Failed defrost heater | Occasional | No warmth felt near the evaporator during a manual defrost test |
| Disconnected temperature fuse | Occasional | Heater circuit interrupted entirely |
| Defrost sensor/thermistor fault | Occasional | Board cannot read evaporator temperature correctly |
| Main control board failure | Less common | Other causes ruled out |
How to fix it
- Power reset
Unplug the refrigerator for about two minutes to reset the unit and let the system attempt the defrost cycle again from scratch.
- Check for visible ice buildup
If you can access the back panel inside the freezer, look for heavy ice encasing the evaporator coil rather than a light, even frost.
- Give it a full cycle to clear
After a reset, allow the unit to run a complete defrost cycle before deciding whether the fault has cleared.
A defrost fault that comes back repeatedly is a defrost-system problem rather than a one-off glitch — the heater, sensor, temperature fuse or drainage path needs proper diagnosis rather than repeated resets.
When to call a professional
If ER dH returns after a reset, have a technician check the defrost heater, sensor, temperature fuse, wiring and drain path — and the main control board if all of those test correctly.
Stop and call a qualified appliance technician or electrician if you find scorched or melted wiring, smell burning, see water that has reached electrical components, or if the fault returns immediately after a repair. Never bypass a safety device — thermal fuses, door interlocks and flood switches fail for a reason, and defeating one converts a broken appliance into a fire or flood risk.
