LG Refrigerator Error “Er dH” — What It Means and Why It Happens
The Er dH code on many LG refrigerators typically indicates a fault in the refrigerator’s defrost system — most often a problem with the defrost heater circuit or related sensors and controls. When the refrigerator’s automatic defrost sequence fails or detects abnormal values, the control board can trigger this error to prevent further damage. Common impacts for users include frost or ice buildup on the evaporator, reduced cooling efficiency, higher energy use, thawed or partially thawed food, and in some cases, the refrigerator cycling continuously or running warmer than normal. While the error seldom presents an immediate electrical hazard, prolonged operation with a failed defrost system can lead to increased compressor stress and potential food safety issues due to inconsistent temperatures.
Common Causes
- Failed defrost heater (open or shorted heater element)
- Faulty defrost thermostat or thermal fuse (doesn’t close during defrost)
- Open or damaged wiring harness/connectors in the defrost circuit
- Malfunctioning main control board (failed relay or sensor input)
- Bad evaporator thermistor/temperature sensor reporting incorrect temps
- Severe ice buildup preventing sensors or heater from operating normally
- Failed evaporator fan causing abnormal temperature readings and tripping diagnostics
Troubleshooting Steps
- Power cycle the refrigerator: unplug or switch off power for 5–10 minutes and then restore power to see if the code clears (this can reset electronics and confirm if the fault is persistent).
- Check for obvious frost/ice: open the freezer and inspect the evaporator cover area for heavy ice buildup — excessive ice often points to a defrost failure.
- Run a diagnostic/test mode (if available): consult your model’s service manual to access LG’s diagnostic mode to read error logs and run component tests for the defrost heater and sensors.
- Inspect wiring and connectors: visually check harnesses around the evaporator and control board for burns, corrosion, or loose connectors. Replace or reseat as needed.
- Test the defrost heater for continuity: disconnect power, remove the evaporator cover and use a multimeter to check continuity across the heater element; an open circuit usually means a failed heater.
- Test the defrost thermostat/thermal fuse: measure continuity at room temperature (or per service manual procedure). Replace if open when it should be closed, or if thermal fuse is blown.
- Check the evaporator thermistor: test resistance at known temperatures and compare to the specification in the service manual — a bad thermistor can send incorrect temp readings.
- Inspect the main control board: look for v