LG · Refrigerator Serious

Er dS — Defrost sensor (thermistor) failure

The defrost thermistor on the evaporator is open, shorted, or out of resistance range — the board can't monitor evaporator temperature during defrost.

Keep using it?
Limited use only
DIY difficulty
Moderate
Verified against
lg.com ↗

How to fix it

  1. Unplug the refrigerator and remove the freezer rear panel.
  2. Locate the defrost thermistor clipped to the evaporator coil.
  3. Measure resistance and compare to the LG service chart at known temperature.
  4. If open or out of spec, replace the thermistor (cheap and quick).
  5. Reseat and inspect the harness connector for corrosion or pinch damage.
  6. Restore power and verify Er dS clears after one defrost cycle.

Why it happens

Typical signs: Er dS on display · Eventual frost buildup on back wall of freezer · Temps may still appear normal at first · Companion Er dH may appear later

  • Open thermistor element Internal break in the NTC sensor.
  • Shorted sensor wiring Pinched/damaged harness near the evaporator.
  • Connector corrosion Moisture in the rear-panel connector.
  • Main board ADC fault Rare; control board input failed.

Parts you may need

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

  • Defrost thermistor Common replacement
    Amazon →

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.