mypros+
Error code reference

LG Refrigerator Error Code Cd

Communication error between Main MICOM and Compressor Driver MICOM on Main PCB.

LG codesLG refrigerator codes

Communication error between Main MICOM and Compressor Driver MICOM on Main PCB.

First step from the service manual

Check communication circuit; verify IC1 PIN47/PIN24 and IC201 PIN48/PIN25 voltages (success: 1V-4V, fail: 0V or 5V).

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 Cd.

  • 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 Cd means on a LG refrigerator

The Cd error code on an LG refrigerator indicates a communication failure between two microcontrollers located on the main PCB: the Main MICOM (the primary control processor) and the Compressor Driver MICOM (the dedicated processor that manages inverter compressor operation). These two chips must continuously exchange data signals to coordinate compressor speed, timing, and feedback. When this communication link breaks down, the refrigerator cannot safely or reliably control the compressor, and the Cd code is triggered to alert the technician to a control board-level fault.

Diagnosing this error begins at the communication circuit itself. The key test points are IC1 PIN47 and PIN24 on the Main MICOM side, and IC201 PIN48 and PIN25 on the Compressor Driver MICOM side. Under normal operating conditions, the voltage at these pins should fall in the range of 1V to 4V, which indicates active, valid communication signals. A reading of 0V points to an open circuit or a failed signal line, while a reading of 5V suggests the line is stuck high, which can indicate a shorted trace, a failed pull-up condition, or a defective IC. Both failure modes confirm the communication path between the two processors is not functioning correctly.

Common root causes include solder joint failures at the IC pins, damaged PCB traces between the two MICOMs, moisture or corrosion on the board affecting signal integrity, or an outright failure of either IC1 or IC201. Because both processors share the same main PCB, a fault in one chip or in the interconnecting circuitry typically means the entire main PCB assembly requires replacement. Physical inspection of the board for burn marks, corrosion, or cracked solder joints is an important early step before condemning the board.

Source: manufacturer service documentation.

Common causes of Cd

  1. 01

    Failed or defective main PCB

    Part replacement

    If either the Main MICOM (IC1) or the Compressor Driver MICOM (IC201) has failed internally, the communication circuit will produce 0V or 5V at the diagnostic pins instead of the expected 1V to 4V range. This typically requires full main PCB replacement.

  2. 02

    Damaged PCB traces between IC1 and IC201

    Wiring / connection

    Physical damage, heat stress, or manufacturing defects can break the signal traces connecting PIN47/PIN24 of IC1 to PIN48/PIN25 of IC201. Inspect the board carefully under magnification for cracked or burned traces.

  3. 03

    Corroded or contaminated communication circuit

    Wiring / connection

    Moisture or corrosion on the main PCB can degrade signal integrity on the communication lines, causing intermittent or complete loss of voltage at the diagnostic pin locations. Visual inspection for white or green corrosion near the IC pins can confirm this cause.

  4. 04

    Failed solder joints at IC pin locations

    Wiring / connection

    Cold or cracked solder joints at IC1 or IC201 pin connections can interrupt the communication signal. This may appear as intermittent Cd faults that come and go with temperature changes or vibration.

  5. 05

    Loose or intermittent PCB connector

    Wiring / connection

    Any connectors on the main PCB that are part of the power supply to the MICOM circuits can cause signal instability if not fully seated. Verify all board connectors are firmly engaged before proceeding to board replacement.

See the test procedure for each cause

Frequently asked questions about Cd

What does Cd mean on a LG refrigerator?
The Cd error code indicates a communication failure between the Main MICOM and the Compressor Driver MICOM, both of which are located on the main PCB. These two processors must exchange signals continuously to control compressor operation, and when that link is broken the refrigerator displays Cd. Diagnosing the fault requires checking voltages at specific IC pin locations on the main control board.
Can I fix the Cd error on my LG refrigerator myself?
The diagnostic process involves measuring voltages at specific pins on integrated circuits on the main PCB, which requires a multimeter and comfort working with electronic components. If the board has visible corrosion or a loose connector, a knowledgeable DIYer may be able to address those issues. However, if the fault is traced to a failed MICOM chip or damaged PCB traces, the main PCB will need to be replaced, which is a more involved repair.
Will resetting my LG refrigerator clear the Cd error code?
A power reset may temporarily clear the Cd code, but if the underlying communication circuit fault remains, the error will return. Because this code points to a hardware failure between two processors on the main PCB, a reset does not address the root cause. Proper diagnosis of the IC pin voltages is needed to determine whether the board requires repair or replacement.
Is it safe to keep using my refrigerator while the Cd code is displayed?
A Cd error means the refrigerator cannot reliably control its compressor, so cooling performance may be compromised or the compressor may not run at all. Continuing to use the refrigerator in this state risks food spoilage and potential damage to the compressor or related components. It is best to address the fault promptly rather than leaving the unit running unattended.
How much does it cost to repair a Cd error on an LG refrigerator?
Repair costs vary depending on the root cause. If the issue is a loose connector or minor corrosion that can be cleaned, the cost may be limited to a service call fee, typically in the range of $75 to $150. If the main PCB requires replacement, parts and labor combined often fall in the range of $200 to $500 or more depending on the specific model and local labor rates.

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