LG · Refrigerator Serious

Er FS — Freezer sensor open/short

The freezer compartment thermistor is reading open or shorted. The board can't accurately read freezer temperature and falls back to a default cycle, so freezer temps drift.

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

How to fix it

  1. Unplug the refrigerator and pull the freezer rear panel.
  2. Locate the freezer thermistor; reseat the plug at the harness.
  3. Measure resistance with a meter and compare to the LG sensor chart.
  4. Replace the thermistor if open, shorted, or out of spec.
  5. If the new sensor still throws Er FS, suspect main control board.
  6. Restore power and verify the code clears.

Why it happens

Typical signs: Er FS on display · Freezer too warm or too cold · Ice cream soft, or freezer burn on items · Compressor cycles abnormally

  • Open NTC thermistor Sensor element failed.
  • Sensor harness break Pinched/cut wire behind the freezer back panel.
  • Bad connector contact Corrosion or loose pin in the wiring connector.
  • Main board ADC channel fault Uncommon, but possible after a surge.

Replace your water filter

A clogged or overdue water filter is a common cause of low water and ice flow on LG refrigerators — they are meant to be changed about every 6 months. The OEM-style filter that fits most LG refrigerators is the LT1000P ($45-55 OEM, $18-28 compatible).

  • LG LT1000P refrigerator water filter OEM water filter
    Amazon →

Not sure which filter fits your model? See the full compatibility guide →

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.

  • Freezer 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.