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Error code reference

LG Refrigerator Error Code Freezer 2nd Digit b

Freezer sensor error

LG codesLG refrigerator codes

Freezer sensor error - connector slipped-out, open-contact, wire cut, short-circuited, or abnormal sensing temperature (+50°C and over, or -50°C and lower).

First step from the service manual

Check voltage between MAIN PCB CN30 #1 and #6; should be within 4.5V~1.0V range.

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

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What Freezer 2nd Digit b means on a LG refrigerator

The Freezer 2nd Digit b error code on an LG refrigerator indicates a fault in the freezer temperature sensor circuit. The main PCB monitors the sensor's output voltage continuously, and this code triggers when the sensed temperature reads +50°C or higher, or -50°C or lower, which fall outside any realistic operating range. These extreme readings indicate the PCB is receiving a signal that does not reflect actual freezer conditions, pointing to a wiring or sensor integrity problem rather than a true temperature extreme.

The freezer sensor is a thermistor, meaning its resistance changes in response to temperature. The main PCB supplies a reference voltage and measures the return voltage at connector CN30 between pins #1 and #6. A healthy circuit should read between 1.0V and 4.5V across those pins depending on the freezer temperature at the time of measurement. A reading outside that range confirms an open circuit, short circuit, or severely out-of-spec thermistor. An open circuit, caused by a cut wire, slipped connector, or broken thermistor lead, will drive the voltage toward the supply rail, producing an abnormally high reading. A short circuit will pull the voltage near zero, producing an abnormally low reading.

Common physical causes include the sensor connector backing out of CN30 on the main PCB, wiring harness damage from ice buildup or mechanical contact, or a failed thermistor element inside the freezer compartment. Connector issues are the most frequent finding and should be inspected before condemning the sensor or PCB.

Source: manufacturer service documentation.

Common causes of Freezer 2nd Digit b

  1. 01

    Slipped or loose connector at CN30

    Wiring / connection

    The sensor wiring connector may have backed out of pins #1 or #6 on the main PCB connector CN30. Inspect the connector for proper seating and any bent or corroded pins.

  2. 02

    Damaged or cut wiring harness

    Part replacement

    The wire running from the freezer sensor to the PCB can be pinched, cut, or broken, especially where it passes through cabinet openings or contacts ice. Check the full harness length for visible damage or breaks.

  3. 03

    Failed freezer thermistor

    Part replacement

    The thermistor element itself may have failed internally, producing an open or short condition that pushes the voltage outside the 1.0V to 4.5V operating range. Confirm with a resistance check before replacing.

  4. 04

    Open contact from corrosion or moisture intrusion

    Wiring / connection

    Moisture in the connector housing can cause corrosion on the terminals, increasing resistance enough to simulate an open circuit. Clean and dry the connector terminals and recheck the voltage at CN30.

  5. 05

    Faulty main PCB

    Part replacement

    If wiring, connectors, and the sensor all test correctly and the CN30 voltage remains outside the 1.0V to 4.5V range, the main PCB may have failed at the sensor input circuit. PCB replacement is a last-resort diagnosis.

See the test procedure for each cause

Frequently asked questions about Freezer 2nd Digit b

What does Freezer 2nd Digit b mean on a LG refrigerator?
This code means the main PCB has detected an abnormal reading from the freezer temperature sensor. The sensor is reporting a temperature at or above +50°C or at or below -50°C, which is outside any realistic range. This points to a wiring fault, a loose connector, or a failed sensor thermistor rather than an actual temperature problem in the freezer.
Can I fix the Freezer 2nd Digit b error myself?
A knowledgeable DIYer can start by checking the sensor wiring connector at main PCB CN30 pins #1 and #6 and measuring the voltage, which should fall between 1.0V and 4.5V. If the connector is simply loose, reseating it may clear the fault. Replacing the sensor thermistor is also a manageable repair, but working near live PCB components requires caution and basic electrical safety knowledge.
Is it safe to keep using my refrigerator while this error is active?
The freezer may not be maintaining proper temperature while this error is active because the control board cannot accurately read freezer conditions. Food safety is at risk if the freezer is not holding 0°F or below. It is best to address the fault promptly and transfer perishable or frozen food to another unit in the meantime if you are unsure whether the freezer is cooling correctly.
Will resetting the refrigerator clear the Freezer 2nd Digit b error?
A power reset may temporarily clear the error display, but the code will return if the underlying fault in the sensor circuit has not been repaired. Resetting does not fix a cut wire, slipped connector, or failed thermistor. The CN30 voltage should be measured and the sensor circuit inspected to resolve the issue permanently.
How much does it cost to repair the Freezer 2nd Digit b error on an LG refrigerator?
If only a connector needs to be reseated, there may be no parts cost at all. A replacement freezer thermistor sensor typically costs between $15 and $50 for the part. If the main PCB is at fault, the board can range from $100 to $300 or more depending on the model. Adding professional labor, total repair costs can range from around $75 to $400 depending on what component has failed.

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