mypros+
Error code reference

LG Refrigerator Error Code Freezer 2nd Digit a

External (ambient) sensor error

LG codesLG refrigerator codes

External (ambient) 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 CN31 #1 and #3; 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.

MyPros+ Max

Get the full diagnostic procedure for Freezer 2nd Digit a.

  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
Get the full procedure

$29/month · Cancel anytime · Or $9.95 3-day pass

What Freezer 2nd Digit a means on a LG refrigerator

The Freezer 2nd Digit 'a' error code on an LG refrigerator indicates a fault with the external ambient temperature sensor. This sensor monitors the surrounding room temperature and feeds that data to the main PCB so the refrigerator can adjust its operation accordingly. When the control board detects a reading outside the acceptable range, specifically at or above +50°C or at or below -50°C, or loses communication with the sensor entirely due to a connector issue or wiring fault, it logs this error. The fault categories include a slipped connector, an open-contact condition, a cut wire, or a short circuit in the sensor circuit.

The primary diagnostic starting point is measuring the voltage between pins #1 and #3 on connector CN31 of the main PCB. A healthy sensor circuit will produce a reading within the 4.5V to 1.0V range, with the actual voltage varying based on ambient temperature. A reading outside this window confirms an electrical fault in the sensor circuit. A reading of approximately 5V typically points to an open circuit such as a disconnected connector or broken wire, while a reading near 0V suggests a short circuit condition. If the voltage is within range but the error persists, the sensor itself may have drifted out of calibration or failed internally.

Source: manufacturer service documentation.

Common causes of Freezer 2nd Digit a

  1. 01

    Loose or disconnected connector at CN31

    Wiring / connection

    The connector linking the ambient sensor to the main PCB at CN31 can work loose over time due to vibration. Inspect the connector and reseat it firmly; this is the most common and easiest fix.

  2. 02

    Failed ambient temperature sensor

    Part replacement

    The sensor itself can fail internally, producing a temperature reading that falls outside the valid range of -50°C to +50°C. If voltage at CN31 pins #1 and #3 is within the 4.5V to 1.0V range but the error persists, the sensor has likely drifted or failed and needs replacement.

  3. 03

    Damaged or cut sensor wiring

    Part replacement

    The wiring harness between the ambient sensor and the main PCB can be pinched, chafed, or cut, creating an open circuit. Inspect the full length of the wire for visible damage and check for continuity.

  4. 04

    Short circuit in the sensor circuit

    Wiring / connection

    A short circuit in the sensor wiring or at the connector terminals will pull the voltage at CN31 toward 0V, outside the valid 1.0V to 4.5V window. Look for bare wires contacting each other or the chassis, and check terminal pins for corrosion or moisture bridging.

  5. 05

    Faulty main PCB

    Part replacement

    If the wiring, connector, and sensor all test as functional, the main PCB may be unable to correctly read or interpret the sensor signal. This is the least common cause and should only be considered after all other components are confirmed good.

See the test procedure for each cause

Frequently asked questions about Freezer 2nd Digit a

What does Freezer 2nd Digit a mean on a LG refrigerator?
The Freezer 2nd Digit 'a' code indicates an error with the external ambient temperature sensor. The control board has detected that the sensor is reading a temperature at or above +50°C or at or below -50°C, or it has lost the signal entirely due to a wiring or connector problem. The fault can stem from a disconnected connector, a cut wire, a short circuit, or a failed sensor.
Can I fix the Freezer 2nd Digit a error myself?
In many cases, yes. Start by locating connector CN31 on the main PCB and checking that it is fully seated. Then measure the voltage between pins #1 and #3; a reading within 4.5V to 1.0V indicates the circuit is intact. If the connector is secure and the voltage is out of range, inspect the wiring harness for damage or replace the ambient sensor.
Is it safe to keep using my refrigerator while this error is active?
The refrigerator will likely continue to run, but its ability to regulate cooling efficiently may be compromised without accurate ambient temperature data. Food safety depends on whether the internal temperatures remain within safe ranges. It is best to address the error promptly and monitor internal temperatures closely in the meantime.
How much does it cost to repair the Freezer 2nd Digit a error on an LG refrigerator?
If the fix is simply reseating a loose connector, there is no parts cost involved. Replacing the ambient temperature sensor typically costs between $15 and $60 for the part alone. If a main PCB replacement is needed, expect parts costs in the range of $100 to $300 or more, with additional labor charges if a technician is hired.
Will resetting the refrigerator clear the Freezer 2nd Digit a error code?
A power reset may temporarily clear the error code from the display, but the code will return if the underlying fault is still present. The ambient sensor circuit must be repaired or the faulty component replaced before the error will clear permanently. Resetting without repairing the root cause does not restore normal sensor operation.

Related LG refrigerator codes

All LG refrigerator codes
View all 485 LG refrigerator codes

78,000+ service manuals · 160,000+ error codes · 55+ brands

Get Started

$29/month · Cancel anytime · Or $9.95 3-day pass