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Error code reference

LG Refrigerator Error Code Fridge 2nd Digit b

Fridge sensor error

LG codesLG refrigerator codes

Fridge 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 #3 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 Fridge 2nd Digit b means on a LG refrigerator

The Fridge 2nd Digit b error code on an LG refrigerator indicates a fault in the refrigerator compartment temperature sensor circuit. This sensor, also called a thermistor, continuously monitors the internal temperature of the fresh food compartment and sends resistance-based readings to the main PCB. The control board interprets this signal as a voltage that should fall within the 4.5V to 1.0V range at connector CN30, pins 3 and 6. When the signal falls outside this window, or when the sensor reports a temperature at or above +50°C or at or below -50°C, the board flags it as an abnormal condition and triggers this error.

The fault can originate from several points in the sensor circuit. A connector that has slipped out of its housing at the PCB or sensor end will cause an open circuit, sending no signal at all. A cut or broken wire in the harness produces the same result. A short circuit within the wiring can pull the voltage out of the acceptable range in the opposite direction. The sensor element itself can also fail internally, causing it to report wildly inaccurate temperatures even when the wiring and connectors appear intact. In all cases, the main PCB cannot trust the compartment temperature data, which disrupts the refrigerator's ability to regulate cooling properly.

Source: manufacturer service documentation.

Common causes of Fridge 2nd Digit b

  1. 01

    Disconnected or slipped connector

    Wiring / connection

    The wiring connector at main PCB CN30 or at the sensor itself may have worked loose over time. Check that the connector is fully seated at both ends, as a partially disconnected connector will cause an open circuit and trigger this error.

  2. 02

    Failed refrigerator compartment thermistor

    Part replacement

    The thermistor element can degrade or fail internally, causing it to read temperatures outside the valid range even when wiring is intact. Confirm the sensor is faulty by checking the voltage at CN30 pins 3 and 6 with the connector attached; a reading outside 4.5V to 1.0V with good wiring points to a bad sensor.

  3. 03

    Damaged or broken wiring harness

    Part replacement

    A cut, pinched, or broken wire between the sensor and the main PCB will interrupt the signal and cause an open-contact fault. Inspect the full length of the sensor harness for visible damage, especially near door hinges or areas where the wire may be routed tightly.

  4. 04

    Short circuit in the sensor circuit

    Part replacement

    A short circuit caused by chafed wiring or moisture intrusion can push the voltage signal outside the 4.5V to 1.0V window. Look for wiring that contacts metal edges or shows signs of moisture exposure that could cause two conductors to contact each other.

  5. 05

    Faulty main PCB

    Part replacement

    If the wiring, connector, and thermistor all test as acceptable but the voltage at CN30 pins 3 and 6 remains outside the specified range, the main PCB itself may be unable to correctly read or supply the reference voltage for the sensor circuit.

See the test procedure for each cause

Frequently asked questions about Fridge 2nd Digit b

What does Fridge 2nd Digit b mean on a LG refrigerator?
This code indicates a fault in the refrigerator compartment temperature sensor circuit. The main PCB has detected that the sensor signal at connector CN30 pins 3 and 6 is outside the valid 4.5V to 1.0V range, or that the sensor is reporting a temperature at or beyond +50°C or -50°C. Possible causes include a disconnected connector, a broken wire, a short circuit, or a failed thermistor. The refrigerator may not cool properly while this fault is active.
How do I fix the Fridge 2nd Digit b error on my LG refrigerator?
Start by checking the wiring connector at main PCB CN30 and at the sensor itself to make sure both are fully seated. Then measure the voltage between CN30 pins 3 and 6 with a multimeter; the reading should be between 1.0V and 4.5V. If the voltage is out of range, inspect the harness for damage such as cuts or pinched wires. If the wiring is intact and the connector is secure, the thermistor itself likely needs to be replaced.
Will resetting my LG refrigerator clear the Fridge 2nd Digit b error?
A reset may temporarily clear the error code from the display, but the code will return if the underlying sensor circuit fault is not corrected. The main PCB will continue to monitor the sensor signal and re-trigger the error any time the voltage remains outside the 4.5V to 1.0V range or the reported temperature stays beyond the valid limits. Diagnosis and repair of the sensor, wiring, or connector is required for a permanent fix.
Is it safe to keep using my LG refrigerator when the Fridge 2nd Digit b error is showing?
Continuing to run the refrigerator with this error is not recommended, as the control board cannot accurately monitor the compartment temperature while the sensor fault is present. This means the fridge may not maintain safe food storage temperatures. Perishable food should be checked and the issue should be diagnosed and repaired as soon as reasonably possible.
How much does it cost to repair the Fridge 2nd Digit b error on an LG refrigerator?
Repair costs depend on which component is at fault. If the fix is simply reseating a loose connector, there may be no parts cost at all. Replacing a failed thermistor typically involves a relatively modest parts cost, while replacing the main PCB is the most expensive outcome. Including labor, total repair costs can range from around $75 to $350 or more depending on the fault and your location.

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