LG · Refrigerator Serious

Er dH — Defrost cycle exceeded time limit

During a defrost cycle the evaporator never reached the target temperature within ~1 hour. The main board logs Er dH, meaning the heater, fuse, sensor, or relay in the defrost circuit is at fault.

Keep using it?
Limited use only
DIY difficulty
Moderate
Typical cost
$30-80
Verified against
lg.com ↗

The fix

Defrost heater

Defrost heater circuit error

$30-80 hard difficulty 120 min Tools: screwdriver, nut driver, multimeter

Diagnose first: Open defrost heater or a failed bimetal thermostat is most common; both live behind the freezer evaporator panel.

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Didn't resolve it? Next suspect: Defrost thermostat / bimetal ($15-30)

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How to fix it

  1. Unplug the unit for 2 minutes, then restore power — clears one-time faults.
  2. If Er dH returns within a day, remove the freezer rear panel.
  3. With a meter, ohm the defrost heater (typical 20–60 Ω); infinity = open, replace it.
  4. Ohm the thermal fuse / bi-metal cold; should read continuity. If open, replace as a kit with the heater.
  5. Check the defrost thermistor against the LG spec chart; replace if out of range.
  6. If all defrost parts test good, replace the main control board (relay failure).

Why it happens

Typical signs: Er dH (or F dH / r dH) on display · Freezer thick with frost on back panel · Both sides eventually warm · Fan noise reduced or stopped · Code returns shortly after a reset

  • Open defrost heater element Glass/sheath heater burns out — the most common single cause.
  • Blown thermal fuse / bi-metal Safety fuse opens after an overheat event and stays open.
  • Defrost sensor (thermistor) failure Open or out-of-spec sensor — board never sees temp climb.
  • Main board relay failed Defrost relay on the PCB won't energize the heater.
  • Wiring/harness break Broken wire to the heater or sensor in the freezer rear panel.

Other parts sometimes needed

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

Related repair guides

How to Defrost a Freezer (Fast and Safely) →Refrigerator Leaking Water on the Floor — Causes and Fixes →Refrigerator Not Cooling — Troubleshooting Guide →

More LG refrigerator codes

22 22 — Compressor relay / inverter control fault 33 33 — Compressor / defrost test fault 67 67 — Door open / not fully closed 88 88 — Power-on display test (not a fault) Er CF Er CF — Condenser fan motor feedback fault Er CO Er CO — Communication error (main board ↔ display)

All LG codes → All refrigerator codes →

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: lg.com.