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LG Aircon CH57 Error Code

Capture the LG CH57 fault correctly, then see what should be checked before parts are quoted. Match the model first; some rows are unofficial or mean different things.

What does LG CH57 mean?

LG CH57 is listed as comms error between outdoor main PCB and inverter PCB, master outdoor unit: Outdoor inverter PCB is not receiving from the main PCB, and slave 1 outdoor unit: Outdoor inverter PCB is not receiving from the main PCB in VRF, Cassette, Ducted rows such as LG Multi V 5 commercial VRF. Official and unofficial listings both cover this code, so the model family decides which one the diagnosis follows. Do not collapse this code across model families; use the model, series, or system type to choose the right row. Confirm the exact model, series, or signal row before accepting a parts quote.

What to do now

Use these steps before customer action, a signal-wire check, or PCB quote.

  • Stop using the unit if CH57 returns

    If CH57 remains displayed or returns during operation, do not attempt a reset the manufacturer does not list; arrange diagnosis.

  • No manufacturer reset steps listed for CH57

    Capture the complete CH57 display and model stickers first. The manufacturer lists no customer reset procedure; do not treat a generic power-cycle as manufacturer guidance.

  • Send these to us

    CH57 error code, a clear display photo, LG model stickers, affected rooms, operating state when the code appeared, whether one room or every room failed, and exact model so the source can be cross-checked

Choose the listing that matches your unit

The same code has more than one listed meaning. Match the model family, the system type and the unit that shows the code before approving parts.

  • Code
    CH57
    What it means
    Comms error between outdoor main PCB and inverter PCB.
    What to check first
    Match this meaning to your installed model and the unit that shows the code, then use the checks below.
  • Code
    LG Multi V 5 commercial VRF — master outdoor unit: Outdoor inverter PCB is not receiving from the main PCB
    What it means
    master outdoor unit: Outdoor inverter PCB is not receiving from the main PCB
    What to check first
    Match this meaning to your installed model and the unit that shows the code, then use the checks below.
  • Code
    LG Multi V 5 commercial VRF — slave 1 outdoor unit: Outdoor inverter PCB is not receiving from the main PCB
    What it means
    slave 1 outdoor unit: Outdoor inverter PCB is not receiving from the main PCB
    What to check first
    Match this meaning to your installed model and the unit that shows the code, then use the checks below.
  • Code
    LG Multi V 5 commercial VRF — slave 2 outdoor unit: Outdoor inverter PCB is not receiving from the main PCB
    What it means
    slave 2 outdoor unit: Outdoor inverter PCB is not receiving from the main PCB
    What to check first
    Match this meaning to your installed model and the unit that shows the code, then use the checks below.

Guidance for your model

Notes that match the code to your exact model. Electrical, refrigerant, wiring, resistance and component checks are for a technician.

  • Detail
    Diagnostic note
    What it says
    Comms error between outdoor main PCB and inverter PCB. Check wiring, fuses and LEDs are lit. If OK either inverter or main PCB defective.
  • Detail
    Diagnostic note
    What it says
    Record 571 and confirm that the master outdoor unit reported it. Have the technician trace the applicable communication wiring, plugs, addressing, and board communication path before replacing PCBs.
  • Detail
    Diagnostic note
    What it says
    Record 572 and confirm that the slave 1 outdoor unit reported it. Have the technician trace the applicable communication wiring, plugs, addressing, and board communication path before replacing PCBs.
  • Detail
    Singapore / model note
    What it says
    Unattributed LG fault-code list; confirm against the installed model/service manual before applying.
  • Detail
    Singapore / model note
    What it says
    LG Singapore lists Multi V 5, but the installed unit nameplate and matching service manual control. Do not apply this row to Multi V i or another LG family. Electrical limits vary by model and supply. Use the installed Singapore supply and model data rather than thresholds from another market.

What to check before repair

Use this split to separate safe evidence capture from the tests a technician should prove before quoting parts.

  • You can check
    Before taking any system action on CH57, take a clear display photo.
    Technician should confirm
    Match CH57 against your model family's listing before parts are quoted.
  • You can check
    Capture the LG indoor and outdoor model stickers so the correct family row is used.
    Technician should confirm
    Test communication terminals, cable continuity, polarity, and outdoor power.
  • You can check
    The manufacturer lists no customer reset procedure for this code. Note whether one room, several rooms, or the whole system is affected.
    Technician should confirm
    Read indoor and outdoor PCB indicators only after the signal path is proven sound.

Wiring or PCB decision

LG CH57 should start with terminal, signal-cable, and power checks. PCB replacement only makes sense after the communication path is proven sound.

  • A loose terminal or bad junction is a targeted repair once the path is confirmed.

  • Signal-wire replacement depends mostly on access through trunking, ceiling, or concealed routes.

  • PCB cost should be weighed against age only after wiring and power checks pass.

LG CH57 questions

What does the LG CH57 error mean?
LG CH57 is listed as comms error between outdoor main PCB and inverter PCB, master outdoor unit: Outdoor inverter PCB is not receiving from the main PCB, and slave 1 outdoor unit: Outdoor inverter PCB is not receiving from the main PCB in VRF, Cassette, Ducted rows such as LG Multi V 5 commercial VRF. Official and unofficial listings both cover this code, so the model family decides which one the diagnosis follows. Do not collapse this code across model families; use the model, series, or system type to choose the right row. Confirm the exact model, series, or signal row before accepting a parts quote.
Can I fix a LG CH57 error myself?
No. CH57 needs a technician's measurement before parts are decided. Before taking any system action on CH57, take a clear display photo. Capture the LG indoor and outdoor model stickers so the correct family row is used.
Is it safe to keep running the aircon with a CH57 error?
If CH57 remains displayed or returns during operation, do not attempt a reset the manufacturer does not list; arrange diagnosis.
What causes a LG CH57 error?
LG CH57 has a listed meaning that depends on the exact model and on which unit shows the code. Use the decoder on this page before assuming a specific cause.
Will a LG CH57 error need a repair or a full replacement?
LG CH57 should start with terminal, signal-cable, and power checks. PCB replacement only makes sense after the communication path is proven sound.
What should I send a technician about a LG CH57 error?
Before booking, send: CH57 error code, a clear display photo, LG model stickers, affected rooms, operating state when the code appeared, whether one room or every room failed, and exact model so the source can be cross-checked.

Where to go next

Confirm the fault

Share the error code, model number and symptoms so we can assess the likely cause.