LG refrigerators are everywhere on my route — French door, side-by-side, top-freezer, you name it. They're well-built machines but they throw error codes that can stop you cold if you don't know the system. I've put this guide together from years of field experience so you have a single reliable reference you can actually use on the job.

LG uses a consistent error code system across most of its modern refrigerator lineup, which is a plus. Once you learn the patterns, you'll recognize codes across models fast. I've noted where codes differ between model families.

Before you do anything else: always check for a recent power outage or voltage event. LG boards are more sensitive to power fluctuations than most. A clean power cycle — unplug for 5 minutes, plug back in — clears phantom codes on LG more reliably than on Samsung or Whirlpool. Try it first. If the code comes back, you've got a real problem.

How to Access LG Refrigerator Diagnostic Mode

Most LG French door and side-by-side models have a hidden diagnostic mode that shows stored error codes and lets you run component tests. Here's how to access it on most models:

  1. Make sure the fridge is plugged in and powered on.
  2. Press and hold the Freezer Temp and Refrigerator Temp buttons simultaneously for about 5 seconds until you hear a chime.
  3. The display will cycle through stored error codes. Write them all down before exiting.
  4. To exit, press any button or wait 30 seconds.
Pro tip: On LG ThinQ models with WiFi, download the LG ThinQ app and connect to the fridge — it pulls diagnostic codes automatically and gives you a plain-English description. Fast for initial triage, though you'll still need this guide for the fix.

Sensor Error Codes

Er FF — Freezer Fan Error

The freezer evaporator fan motor isn't running or isn't being detected by the control board. This is one of the most common LG codes I see in the field. First step: defrost the unit completely. Ice buildup around the fan blade is the #1 cause — the motor is usually fine. A full manual defrost (unplug, leave doors open 24–48 hours with towels on the floor) resolves it more often than not.

If the code returns within a week after defrost, your defrost system isn't working. Check the defrost heater and defrost thermostat (see Er dH below). If defrost checks out and the fan still won't spin freely by hand, replace the motor. Part: EAU61524007 or model equivalent.

Er rF — Refrigerator Fan Error

Same as Er FF but for the fresh food section fan. Less common than the freezer fan issue, but same diagnostic approach — defrost first, then check the motor. On French door models, this fan sits behind the rear wall of the fresh food section.

Er CF — Condenser Fan Error

The condenser fan at the bottom rear of the fridge isn't running. Pull the fridge away from the wall and check if the fan area is clogged with dust, pet hair, or debris. A clogged condenser fan is a textbook cause of "fridge isn't cooling" calls that homeowners have been sitting on for weeks. Clean it out first. If the fan area is clear and the fan still won't spin, replace the motor. Part: EAU36519303 or equivalent.

Er FS / Er rS — Freezer or Fridge Sensor Error

The temperature thermistor in the freezer (Er FS) or fresh food (Er rS) section has failed. Test the sensor with a multimeter — at room temperature it should read approximately 5k ohms. Out of range means replace it. These are usually inexpensive parts and a straightforward swap. Parts typically run $15–$35 and take 20–30 minutes to replace.

Er IS — Ice Maker Sensor Error

The ice maker temperature sensor has failed. Check the sensor wiring harness for damage first. If the harness is intact, replace the sensor. On some models this is integrated into the ice maker assembly and requires replacing the whole unit.

Er dS — Defrost Sensor Error

The defrost thermistor has failed. This sensor monitors the evaporator temperature during the defrost cycle and tells the board when to stop heating. A failed defrost sensor typically causes one of two problems: the unit never defrosts (ice builds up on the back wall) or it defrosts too long (water leaks into the fridge compartment or the floor). Replace the defrost thermistor and inspect the bi-metal thermostat while you're in there.

Defrost System Error Codes

Er dH — Defrost Heater Error

The defrost heater circuit has an open circuit. This is the most common root cause behind Er FF on LG units — the heater fails, ice builds up, and eventually blocks the fan. Test the defrost heater for continuity. No continuity = open heater, replace it. Also test the bi-metal thermostat in series with the heater — it's a thermal fuse that opens at a set temperature and often fails alongside the heater on older units.

Heads up: On LG linear compressor models (most French door units from 2013 onward), defrost issues are extremely common. LG has issued several extended warranty programs for linear compressor failures. Before quoting a full repair, check whether the unit's serial number falls under an active LG service bulletin — it may save your customer significant money.

Er CO — Communication Error

The main control board and one of the sub-boards (display board, ice maker board, or linear compressor inverter board) have lost communication. Check all wiring harness connections first — on LG French door units, the door wiring harnesses run through the hinges and take wear over time. If all connections are tight and the code persists, identify which sub-board is failing by swapping if you have a spare, or use a multimeter to test continuity on the communication lines.

Er 1F / Er 2F — Ice Maker Errors

Er 1F indicates the ice maker fan isn't running. Er 2F is a general ice maker malfunction code. For Er 1F, check the ice maker fan motor directly. For Er 2F, run through the ice maker systematically: water supply valve, fill tube for freezing, ice maker motor, and temperature sensor. LG ice makers on French door models have a higher-than-average failure rate — if the unit is out of warranty and the ice maker has already been serviced once, a full ice maker assembly replacement is often the right call.