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Error code reference

LG Refrigerator Error Code D-Heater

Defrost heater error

LG codesLG refrigerator codes

Defrost heater error - defrost heater circuit failure detected.

First step from the service manual

Enter TEST 2 MODE and check voltage between pins 6 (BL/WH) and 5 (BN) of CON3 for 230VAC.

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

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What D-Heater means on a LG refrigerator

The D-Heater error code on an LG refrigerator indicates a fault in the defrost heater circuit. The control board monitors the defrost heater for proper electrical continuity and current flow during the defrost cycle. When the board detects an open circuit, a short, or insufficient current in the heater circuit, it logs this fault and displays the D-Heater error. The defrost heater is responsible for melting frost buildup on the evaporator coils, and a failure here will eventually lead to ice accumulation, restricted airflow, and degraded cooling performance.

Diagnosing this error begins with entering TEST 2 MODE on the refrigerator and measuring voltage between pins 6 (BL/WH) and 5 (BN) of connector CON3. The expected reading is 230VAC. If voltage is present at CON3 but the heater is not operating, the heater element itself is likely open or failed. If voltage is absent, the fault points upstream toward the control board, wiring harness, or a related safety component such as the thermal fuse or defrost thermostat in the circuit. Each of these components must be systematically tested to isolate the failure point.

Common failure modes include a burned-out heater element, a blown thermal fuse caused by an overheating event, or wiring damage within the harness connecting CON3 to the heater assembly. Corroded or loose connector pins at CON3 can also interrupt the circuit and produce this code. In rarer cases, a failed control board that cannot supply the 230VAC output to the heater circuit will trigger the error even when all downstream components test good.

Source: manufacturer service documentation.

Common causes of D-Heater

  1. 01

    Failed defrost heater element

    Part replacement

    The heater element itself can burn out or develop an open circuit over time. If 230VAC is confirmed at CON3 pins 6 and 5 but the heater does not operate, test the heater element directly for continuity. An open reading confirms the element needs replacement.

  2. 02

    Blown thermal fuse

    Part replacement

    A thermal fuse in the defrost circuit protects against overheating and is a common single-point failure. A blown thermal fuse breaks the circuit completely and will cause the D-Heater error. Test the fuse for continuity and replace it if open.

  3. 03

    Damaged or corroded wiring harness

    Wiring / connection

    Wiring between the control board connector CON3 and the heater assembly can develop breaks, corrosion, or loose terminal connections. Inspect the BL/WH and BN wires along their full length and check connector pins for corrosion or backing out of the housing.

  4. 04

    Failed defrost thermostat

    Part replacement

    The defrost thermostat is a safety device that opens the circuit if the evaporator reaches a certain temperature. If it has failed in the open position, it will interrupt heater operation even when the heater element is intact. Test for continuity at room temperature, where it should read closed.

  5. 05

    Control board not supplying output voltage

    Part replacement

    If no 230VAC is measured at CON3 pins 6 and 5 during TEST 2 MODE and all downstream components test good, the control board may have failed and is not producing the required output voltage to drive the heater circuit.

See the test procedure for each cause

Frequently asked questions about D-Heater

What does D-Heater mean on a LG refrigerator?
The D-Heater code indicates that the LG refrigerator's control board has detected a fault in the defrost heater circuit. The defrost heater is responsible for melting frost off the evaporator coils during the defrost cycle. When the circuit shows an open, a short, or no current flow, the board logs this error. Common causes include a failed heater element, a blown thermal fuse, or a wiring fault in the circuit.
Can I fix the D-Heater error myself on my LG refrigerator?
Some steps in diagnosing this error require working with 230VAC live circuits, which carries a serious shock risk and should only be performed by a qualified technician. A knowledgeable DIYer with a multimeter can safely check components for continuity with the unit unplugged, such as testing the heater element, thermal fuse, and defrost thermostat. However, live voltage testing at CON3 during TEST 2 MODE should be left to someone with proper electrical safety training.
Is it safe to keep using my LG refrigerator when the D-Heater code is showing?
Continuing to run the refrigerator with a defrost heater fault will allow frost to accumulate on the evaporator coils over time, which will progressively reduce cooling performance and can eventually cause the unit to stop cooling entirely. There is no immediate electrical safety hazard to food or the home from the code itself, but the appliance should be repaired promptly to prevent food spoilage and potential secondary damage to the evaporator or fan components from ice buildup.
How much does it cost to repair the D-Heater error on a LG refrigerator?
Repair costs vary depending on which component has failed. A defrost heater element or thermal fuse replacement is typically on the lower end of the cost range, often falling between $100 and $250 including parts and labor. If the control board is the root cause, costs can rise to between $200 and $450 or more depending on the specific model and labor rates in your area. Getting a diagnostic visit quote first is advisable before committing to the repair.
Will resetting my LG refrigerator clear the D-Heater error code?
A power reset may temporarily clear the D-Heater code from the display, but the error will return as soon as the control board runs another defrost cycle and detects the same circuit fault. Resetting the unit does not repair any of the underlying causes such as a failed heater element, blown fuse, or damaged wiring. The code will continue to appear until the defective component is identified and replaced.

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