FixByModel
Er dS

LG Er dS: Defrost sensor failure

The defrost sensor (thermistor) that monitors the evaporator during the defrost cycle has failed or read out of range, so frost can build on the coil.

May need a technician

By the FixByModel editorial team · Verified 2026-09 · Researched against manufacturer support & repair references (below)

Most likely causes

  1. Failed or shorted defrost thermistor
  2. Damaged or disconnected sensor wiring
  3. Corroded sensor connector
  4. Control board fault reading the sensor
Before you start — unplug the refrigerator before working on it. Mind sharp metal edges, and never open the sealed refrigerant system — compressor, sealed-system and refrigerant work must be left to a qualified technician.

Step-by-step fix

1Reset powerUnplug the refrigerator or trip its breaker, wait about 5 minutes, then restore power to see if the code clears.
2Watch for frostCheck for heavy frost on the rear freezer wall, which confirms the defrost monitoring has failed.
3Avoid sealed-system workThis is a sensor-circuit fault and does not involve the refrigerant system.
4Schedule a technicianHave a professional test the defrost sensor resistance and replace the thermistor or repair its wiring.

Still showing Er dS?

If you’ve worked through every step and Er dS keeps returning, an internal part likely needs testing and replacement. That’s a job for a qualified appliance technician, who can measure the suspect part against the service-manual spec before replacing it.

Which models this applies to

LG refrigerators. LG refrigerators with adaptive/automatic defrost and a defrost thermistor

FAQ

What does LG Er dS mean?

Defrost sensor failure. The defrost sensor (thermistor) that monitors the evaporator during the defrost cycle has failed or read out of range, so frost can build on the coil.

What causes LG Er dS?

The most likely cause is failed or shorted defrost thermistor. Other causes include Damaged or disconnected sensor wiring; Corroded sensor connector; Control board fault reading the sensor.

Can I fix LG Er dS myself?

Some checks are DIY, but this code often points to an internal component, so it may need a qualified technician.