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Error code reference

LG Refrigerator Error Code F-112

F-DEF Heater Error (Freezer Defrost Heater)

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F-DEF Heater Error (Freezer Defrost Heater) - wire harness slipped out, contact error, wire cut, defective temp fuse, or defrosting does not finish after 70-minute continuous heating.

First step from the service manual

Separate MAIN PCB CN70 and CN71 from PCB, check continuity between CN70 Brown and CN71 Orange; resistance should be within 55 ohm ±7%.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What F-112 means on a LG refrigerator

The F-112 error code on an LG refrigerator indicates a fault in the freezer defrost heater circuit, designated as an F-DEF Heater Error. This code is triggered when the control system detects an interruption or abnormality in the defrost heater loop, or when the heater runs continuously for 70 minutes without completing the defrost cycle. The defrost heater is a critical component responsible for melting accumulated frost off the evaporator coils in the freezer compartment. When this process fails, ice builds up on the coils and eventually restricts airflow, causing cooling performance to degrade throughout the entire refrigerator.

The electrical circuit for the freezer defrost heater runs through the main PCB connectors CN70 and CN71. The first diagnostic step involves disconnecting these connectors from the PCB and measuring continuity between the CN70 Brown wire and the CN71 Orange wire. The resistance across this circuit should read approximately 55 ohms, within a tolerance of plus or minus 7%. A reading outside this range points to a fault in the heater element itself or in the wiring connecting it to the board. A reading of infinite resistance (open circuit) indicates a broken wire, a failed thermal fuse, or a disconnected harness.

The thermal fuse is a one-time protective device wired in series with the defrost heater. If the freezer compartment exceeds a safe temperature threshold during a defrost cycle, this fuse opens permanently and must be replaced. Wire harness issues, including connectors that have vibrated loose, pins that have backed out of their housings, or wiring that has been cut or chafed, are also common causes of this fault. If the heater circuit checks out electrically but the defrost cycle still fails to complete within 70 minutes, the heater element itself or the defrost thermostat may be defective.

Source: manufacturer service documentation.

Common causes of F-112

  1. 01

    Disconnected or loose wire harness

    Wiring / connection

    The connectors at CN70 and CN71 on the main PCB can vibrate loose or slip out over time, breaking the circuit to the defrost heater. Inspect both connectors for secure seating and check for bent or backed-out pins.

  2. 02

    Failed thermal fuse

    Part replacement

    The defrost circuit includes a thermal fuse that opens permanently if the heater circuit overheats. A blown thermal fuse will show as an open circuit (infinite resistance) when testing continuity between CN70 Brown and CN71 Orange.

  3. 03

    Defective defrost heater element

    Part replacement

    The heater element itself can burn out or develop an open circuit, preventing any heat from being generated during the defrost cycle. This will also produce an out-of-range or open resistance reading during the 55 ohm continuity test.

  4. 04

    Cut or damaged wiring

    Part replacement

    Wiring between the heater assembly and the PCB connectors can be cut, pinched, or chafed by sharp sheet metal edges or ice buildup. A visual inspection of the harness routing from the evaporator to the board is necessary to identify this type of damage.

  5. 05

    Defrost cycle not completing within 70 minutes

    Part replacement

    If excessive frost accumulation forces the heater to run beyond the 70-minute limit before the defrost thermostat terminates the cycle, the PCB will log this error. This can point to a failing defrost thermostat or a heater that is producing insufficient heat output.

See the test procedure for each cause

Frequently asked questions about F-112

What does F-112 mean on a LG refrigerator?
F-112 is a freezer defrost heater error, meaning the refrigerator has detected a problem with the circuit that powers the defrost heater on the freezer evaporator coils. The fault can be caused by a loose or disconnected wire harness connector, a cut wire, a blown thermal fuse, a failed heater element, or a defrost cycle that ran for more than 70 minutes without completing. The primary diagnostic step involves testing the resistance between specific wires at the main PCB connectors CN70 and CN71, where a healthy circuit should measure approximately 55 ohms.
Can I fix the F-112 error myself?
Some causes of F-112 can be addressed without replacing parts, such as reseating a loose connector at CN70 or CN71 on the main PCB. However, diagnosing the fault properly requires a multimeter to test circuit continuity and resistance. If the thermal fuse or heater element has failed, those parts will need to be replaced, which involves accessing the freezer evaporator compartment by removing interior panels.
Is the F-112 error on an LG refrigerator a safety concern?
The error itself is not an immediate safety hazard, but it does mean the freezer is not defrosting correctly. Over time, frost will accumulate on the evaporator coils, restricting airflow and causing the refrigerator to stop maintaining safe food storage temperatures. The issue should be diagnosed and repaired promptly to avoid food spoilage.
How much does it cost to repair an F-112 error on an LG refrigerator?
Repair costs vary depending on the root cause. If only a wire harness needs to be reseated, there is no parts cost. Replacement thermal fuses and defrost heater elements typically range from 15 to 60 dollars in parts. If professional repair service is needed, total costs including labor can range from 100 to 300 dollars or more depending on your location and the specific parts required.
Will resetting my LG refrigerator clear the F-112 error code?
Performing a reset by unplugging the refrigerator for a few minutes may temporarily clear the error code from the display, but it will not fix the underlying electrical fault or component failure. The code will return once the refrigerator runs through its next defrost cycle if the problem has not been corrected. A proper repair requires identifying and resolving the specific cause, whether that is a wiring issue, a blown thermal fuse, or a failed heater element.

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