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Error code reference

LG Refrigerator Error Code Freezer 1st Digit b

Damper heater error

LG codesLG refrigerator codes

Damper heater error - damper heater sensed as open error due to connector slipped-out, open-contact, or wire cut.

First step from the service manual

Unplug MAIN PCB CN90 from PCB, check resistance between #1 (BLACK) and #2 (BROWN); should read 140~160 Ohm.

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

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What Freezer 1st Digit b means on a LG refrigerator

The LG refrigerator Freezer 1st Digit b error code indicates a damper heater open-circuit fault. The damper heater is a small resistive heating element located at the damper assembly, which prevents ice buildup that could obstruct airflow regulation between the freezer and fresh food compartments. When the main control board detects that the damper heater circuit reads as open rather than within its expected resistance range, it logs this error. The fault is specifically triggered by an open-circuit condition, meaning current cannot flow through the heater element or its wiring.

The primary diagnostic step involves disconnecting connector CN90 from the main PCB and measuring resistance between pin #1 (BLACK wire) and pin #2 (BROWN wire). A properly functioning damper heater will read between 140 and 160 ohms. A reading of infinite resistance (OL) confirms an open circuit in the heater element or its wiring harness. A reading significantly outside the 140 to 160 ohm range also indicates a fault condition requiring further investigation.

The three most common root causes are a slipped-out connector at CN90, an open contact within the connector or wiring harness, or a physically cut or broken wire. Because this is an electrical continuity fault rather than a thermistor reading fault, temperature-related misreadings are not the culprit. Technicians should inspect the full wiring path from the PCB connector through to the damper assembly, checking for chafed insulation, pinched wires, or loose terminals before condemning the heater element itself.

Source: manufacturer service documentation.

Common causes of Freezer 1st Digit b

  1. 01

    Slipped-out connector at CN90

    Wiring / connection

    The CN90 connector on the main PCB can work loose over time due to vibration, causing an open circuit in the damper heater circuit. Check that CN90 is fully seated on the PCB before testing resistance.

  2. 02

    Open contact within the wiring harness

    Wiring / connection

    A terminal inside the connector or inline along the harness can develop a poor or broken contact without visible external damage. Measuring resistance between pin #1 (BLACK) and pin #2 (BROWN) at CN90 will confirm whether continuity is lost.

  3. 03

    Cut or broken wire

    Part replacement

    The wire between the main PCB and the damper heater may be physically cut or broken, often due to pinching near cabinet edges or ice formation around the damper assembly. Visually inspect the full length of the wiring run for damage.

  4. 04

    Failed damper heater element

    Part replacement

    The resistive heater element itself can fail internally, resulting in an open circuit. If wiring and connectors all check out but resistance still reads outside 140 to 160 ohms, the heater element requires replacement.

  5. 05

    Faulty main PCB

    Part replacement

    If wiring, connectors, and the heater element all test within specification, the main PCB may have a failed output circuit for the CN90 damper heater connection. This is the least common cause and should only be suspected after all other components are confirmed good.

See the test procedure for each cause

Frequently asked questions about Freezer 1st Digit b

What does Freezer 1st Digit b mean on a LG refrigerator?
The Freezer 1st Digit b code indicates a damper heater open-circuit error. The control board has detected that the damper heater circuit, measured at connector CN90 on the main PCB, is not showing the expected resistance of 140 to 160 ohms. This points to a disconnected, broken, or open-contact condition in the heater wiring or the element itself.
How do I fix the Freezer 1st Digit b error on my LG refrigerator?
Start by unplugging the refrigerator and disconnecting connector CN90 from the main PCB. Measure resistance between pin #1 (BLACK) and pin #2 (BROWN) using a multimeter. If you read infinite resistance or a value well outside 140 to 160 ohms, trace the wiring from CN90 to the damper heater, looking for loose connectors, broken wires, or a failed heater element. Repair or replace whichever component is faulty.
Is it safe to keep using my LG refrigerator while this error is active?
Short-term use is generally possible, but the damper heater plays a role in preventing ice buildup at the damper assembly, which regulates airflow between compartments. Over time, ice accumulation could impair cooling performance in both the freezer and fresh food sections. Prompt repair is recommended to avoid potential food spoilage or secondary damage.
Will resetting my LG refrigerator clear the Freezer 1st Digit b error code?
A power reset may temporarily clear the displayed code, but the error will return if the underlying open-circuit fault in the damper heater wiring or element has not been corrected. The control board will re-detect the fault the next time it checks the CN90 circuit. A permanent fix requires diagnosing and repairing the faulty wiring, connector, or heater element.
How much does it cost to repair the Freezer 1st Digit b error on an LG refrigerator?
Repair costs vary depending on the root cause. If only a connector needs reseating, there may be no parts cost, though a service call fee typically runs between $75 and $150. Replacing a wiring harness or damper heater element generally adds $30 to $120 in parts, plus labor. If the main PCB is at fault, board replacement can range from $150 to $400 or more depending on the model.

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