LG aircon CH57 error code
Use this LG CH57 error code guide to decide when to stop resetting, what to capture, and what to check before parts are quoted. Cross-check the exact model because the row is unofficial.
What does LG CH57 mean?
LG CH57 is listed as comms error between outdoor main PCB and inverter PCB in the loaded residential diagnostic rows. The loaded row is unofficial, so do not approve parts from this code alone. Confirm the exact model, series, or signal row before accepting a parts quote.
Loose, corroded, crossed, or damaged indoor-outdoor signal wiring.
Terminal block, connector, or junction fault on the indoor or outdoor side.
Indoor or outdoor PCB communication circuit fault after wiring is proven sound.
What to do now
Use these steps before another reset, signal-wire check, or PCB quote.
Stop using the unit if CH57 returns
If CH57 returns after one reset, stop repeated restarts and get the matching source row diagnosed.
Reset CH57 once
Capture the CH57 display first, then power-cycle once only and note whether the same fault returns.
Send these to us
CH57 error code, a clear display photo, LG model stickers, affected rooms, reset result, whether one room or every room failed, and exact model so the source can be cross-checked
Source-specific guidance
These diagnostic-reference notes help match the code to the exact model. Electrical, refrigerant, wiring, resistance, and component checks are technician work, not DIY steps.
| Source detail | What it says |
|---|---|
| Source repair action | Comms error between outdoor main PCB and inverter PCB. Check wiring, fuses and LEDs are lit. If OK either inverter or main PCB defective. |
| Singapore / model note | Unattributed LG fault-code list; confirm against the installed model/service manual before applying. |
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 | Technician should confirm |
|---|---|
| Before resetting CH57, take a clear display photo. | Match CH57 against the exact model-family source row before quoting parts. |
| Capture the LG indoor and outdoor model stickers so the correct family row is used. | Test communication terminals, cable continuity, polarity, and outdoor power. |
| Treat the code as a starting point and note the exact symptoms because this row is not brand-official yet. | Read indoor and outdoor PCB indicators only after the signal path is proven sound. |
What changes the next step
These clues decide whether the first check is room-side, shared outdoor-side, refrigerant-side, source-table, or model-family confirmation.
| What you see | What it points to |
|---|---|
| Only one indoor unit shows CH57. | The affected room, indoor board path, wiring route, or local component should be checked first. |
| Several rooms or the outdoor unit show the same CH57 fault. | The shared outdoor side, power path, communication trunk, or refrigerant circuit needs priority checking. |
| The fault returns immediately after one reset. | Start with the source-row diagnostic branch before approving parts. |
| The model family is different from the row you found online. | Use the model or series filter first; same-looking codes can still belong to different diagnostic tables. |
| The model belongs to the loaded residential diagnostic rows. | The loaded row is unofficial, so do not approve parts from this code alone. Use the matching source row before quoting parts. |
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?
Can I fix a LG CH57 error myself?
Is it safe to keep running the aircon with a CH57 error?
What causes a LG CH57 error?
Will a LG CH57 error need a repair or a full replacement?
What should I send a technician about a LG CH57 error?
Confirm the fault
Share the error code, model number and symptoms so we can assess the likely cause.
Not the right code?
Browse the full LG list or check a few codes in the same fault category.
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Read next
Use these if the quote mentions the parts, checks, or repair path this code points to.