LG refrigerators are equipped with advanced diagnostic systems that detect faults and display error codes when a problem occurs. These codes help identify issues related to cooling performance, fans, sensors, defrost systems, ice makers, water flow, communication errors, and control board failures.

Understanding error codes on LG refrigerators can help you quickly diagnose the problem and determine whether it is a simple fix or a repair that requires a qualified technician.

⚠️ Important Safety Note

DANGER: Electric Shock Hazard

Always unplug the refrigerator or shut off the circuit breaker before inspecting electrical components, wiring, or fans. Use a digital multimeter (DMM) with caution when testing live voltage.

How to Read & Reset Error Codes On LG Refrigerator

• On-Screen Display: Error codes appear on the digital control panel, usually prefixed by “Er” (e.g., “Er FF” or “Er rS”).
• Smart Diagnosis™: For app-enabled models, open the LG ThinQ® app, navigate to Smart Diagnosis, and hold your phone near the speaker icon on the refrigerator to transfer diagnostic data.
• How to Reset: Most codes clear automatically once the fault is fixed. To clear a temporary glitch, unplug the refrigerator for 5 to 10 minutes, then plug it back in.

Master Index of Error Codes On LG Refrigerator

Fan Motor Errors

Error Code	Description	Potential Causes	Troubleshooting & Solutions
E CF	Condenser Fan Error	Blocked fan blade, loose harness at the main board, dead motor.	Check for debris under the fridge. Verify 12 Vdc at the motor. Clean coils.
E FF	Freezer Fan Error	Ice buildup is binding the blade, the motor is bad, and the harness is open.	Defrost the freezer. Check fan blade rotation. Verify 12 Vdc to the motor.
E rF	Refrigerator Fan Error	Evaporator fan failure, wiring issue, and main PCB fault.	Inspect the fresh food compartment fan. Test voltage at the main board.
E IF	Ice Maker Fan Error	Ice jam blocking the fan, failed motor harness.	Clear ice blockages in the door duct. Check fan resistance.

Temperature & Sensor Errors

Error Code	Description	Potential Causes	Troubleshooting & Solutions
F dS	Defrost Sensor Error	Short or open circuit in defrost thermistor assembly.	Test sensor resistance (approx. 9.8 kΩ at 25°C). Replace if failed.
E FS	Freezer Sensor Error	Defective freezer room thermistor or loose plug.	Check harness continuity. Test sensor resistance (approx. 2.3 kΩ at 25°C).
E rS	Refrigerator Sensor (Upper)	Defective fresh food compartment sensor.	Measure resistance (approx. 9.8 kΩ at 25°C) at the main board plug.
E r2	Refrigerator Sensor 2 Error	Secondary fresh food sensor malfunction.	Treat identically to E rS. Check secondary sensor harness.
E HS	Humidity Sensor Error	Internal humidity sensor failure or loose harness.	Check voltage drop at the sensor pinouts. Replace sensor assembly.
E rt	Room Temperature Sensor	Ambient sensor failure (outside the cabinet).	Check the top hinge cover sensor. Test for approx. 9.8 kΩ at 25°C.
E Id	Craft Ice Maker Sensor	Sensor fault in the spherical ice tray system.	Measure sensor resistance. Ensure wire harness at ice maker is secure.
E IS	Standard Ice Maker Sensor	Built-in icemaker thermistor failure.	Inspect the plug beneath the ice maker assembly. Replace if shorted.

Communication Failures

Error Code	Description	Potential Causes	Troubleshooting & Solutions
E CO	Main-to-Display Comm Error	Broken wire in top door hinge, loose plug at display/PCB.	Inspect the top door hinge wire bundle for pinches or cuts. Reseat plugs.
E C1	Dispenser Comm Error	Communication line dropped to dispenser board.	Remove dispenser panel and check wire harness connections.

Auto-Door & Smart Drawer Errors

Error Code	Description	Potential Causes	Troubleshooting & Solutions
E AS	Auto-Door Switch Error	Misaligned door, broken reed switch, bad magnet.	Test the reed switch using a magnet and a multimeter. Check alignment.
L AS / r AS	Left / Right Auto Drawer Switch	Actuator switch failing on automated drawer models.	Inspect the specific drawer track switch and wiring harness.
I LS / U LS	Smart Auto Drawer / Lift Switch	Sensor failure on automated lift/drawer mechanisms.	Check for physical obstructions blocking the lifting tracks.
E dL / E dr	Left / Right Auto Drawer Module	Motor failure, broken gear, or Hall IC fault.	Check hall sensor voltage (5–10 Vdc). Replace motorized drawer track.
E Ad / I Ld	Auto Door / Smart Drawer Module	The control module cannot actuate the mechanical assembly.	Verify main board power output to the door/drawer drive modules.
U Ld	Smart Auto-Lift Module Error	Lift motor or control module failure.	Check wiring harness connector at the base of the lift unit.

Defrost & Ice System Errors

Error Code	Description	Potential Causes	Troubleshooting & Solutions
F dH	Defrost Heater Fault	The defrost loop didn’t heat past 8°C within 2 hours.	Test defrost heater (approx. 50 Ω) and thermal fuse (0.1–1.2 Ω).
E IU	Craft Ice Maker Unit Error	Stepper motor, heater, or gear alignment failure.	Clear jammed ice. Check craft ice assembly wiring. Replace unit if stuck.
E It	Standard Ice Maker Unit Error	Jammed ice ejector arm, mechanical motor failure.	Clear ice bucket overfill. Run a manual ice maker test cycle.

System Alerts & Environment Codes

Error Code	Description	Potential Causes	Troubleshooting & Solutions
OFF / OF A	Demo / Showroom Mode	Accidentally enabled during cleaning or delivery.	To turn off: Press and hold the Refrigerator and Express Freeze buttons simultaneously with the door open until a beep sounds.
Sb / 5b	Sabbath Mode	Religious observance mode active.	To turn off: Press and hold the Smart Grid and Freezer buttons (or see the model manual). Auto-exits after 96 hours.
E CH	High-Side Cycle Leak	Refrigerant leak, failed 3-way valve, compressor fault.	🛑 Do Not DIY. Requires a certified EPA technician to repair the closed loops.
E CL	Low-Side Cycle Leak	Evaporator loop leak or low refrigerant.	🛑 Do Not DIY. Contact LG Authorized Service immediately.
E FU	Failing Unit Error	Complete cooling loss, door left open, failed compressor.	Check door gaskets. Clean condenser coils. Verify if the compressor is running.
E gF	Flow Meter Sensor Error	Low water pressure, a kinked water line, or a bad flow meter.	Straighten the water line behind the fridge. Ensure the home water valve is fully open.
E gS	Gas Sensor Error	Pure N Fresh™ ventilation system sensor fault.	Replace the air filter element and inspect the filter housing harness.
Hi	High Ambient Temperature	Kitchen/room temperature is above 50°C (122°F).	Cool down the room environment. Ensure adequate clearance around the unit.
Lo	Low Ambient Temperature	Kitchen/room temperature is below -10°C (14°F).	Do not operate the unit in unheated garages or porches. Move to a warm room.

Electrical Component Specifications

If you are using a multimeter to diagnose the source of an error code, use these standard LG target values to identify components that have failed:

Sensors & Electronics

Component	Test Parameter	Expected Value	Failure Sign
Defrost Sensor	Resistance	~9,800 Ω at 25°C (77°F)	OL (Open Line) or short circuit
Freezer Sensor	Resistance	~2,300 Ω at 25°C (77°F)	OL or short circuit
Refrigerator Sensor	Resistance	~9,800 Ω at 25°C (77°F)	OL or short circuit
Room Temp (Ambient)	Resistance	~9,800 Ω at 25°C (77°F)	OL or short circuit
Hall Sensor (Drawers)	Resistance	~17.4 kΩ (Black to Red wire)	No resistance reading
Hall Sensor (Drawers)	Input Voltage	5 to 10 Vdc	0 Vdc from the Main PCB

Heating Elements

Component	Test Parameter	Expected Value	Failure Sign
Defrost Heater	Resistance	~50 Ω	OL (Burned-out heating element)
Thermal Fuse	Resistance	0.1 to 1.2 Ω (at 76°C)	OL (Blown thermal safety limit)

Fan Motor Voltage Checkpoints

For both 3-wire and 4-wire BLDC fan configurations:

[ VCC (Red) ] ------------ ~12 Vdc (Main Power Source) ------------> [ GND (Black) ]
[ FG (White) ] ----------- ~2.4 Vdc (Rotation Feedback Signal) ----> [ GND (Black) ]
[ PWM (yellow) ] ----------- 1.2 to 4.6 Vdc (Speed Control Signal) --> [ GND (Black) ]

• Note: 3-wire fan versions do not include the yellow PWM control wire. If VCC is receiving 12 Vdc but the FG feedback reads 0 Vdc while the fan is stuck, the motor is dead and must be replaced.

Advanced Diagnostic Steps & Control Board Testing

When error codes persist after initial resets, testing components directly from the Main Power Control Board (PCB)—usually located in a panel on the back or top of the refrigerator—saves you from tearing apart the interior liners.

Step-by-Step Main Board Test Procedure

1. Power Down: Unplug the refrigerator and wait 60 seconds.
2. Access the PCB: Remove the metal cover plate on the back or top of the cabinet.
3. Locate Test Buttons: Most LG main boards feature a small micro-switch tactile button labeled TEST1 (or simply TEST).
4. Forced Test Mode: Plug the unit back in and press the test button to manually force components on for multimeter testing:
   • Press 1 Time (Forced Operation): Forces the compressor and all fans (freezer, refrigerator, and condenser) to run at maximum speed. Perfect for diagnosing fan voltage dropouts.
   • Press 2 Times (Forced Defrost): Turns off the compressor and activates the defrost heater loop. Use this to immediately check if 120 Vac is being sent to the defrost heater assembly.
   • Press 3 Times (Reset): Returns the refrigerator to normal operating conditions.

Final Conclusion

Error codes on LG refrigerators are essential diagnostic tools that help identify faults quickly and accurately. By understanding how fan systems, sensors, ice makers, and control boards interact, you can significantly reduce troubleshooting time and avoid unnecessary repairs.