CH52 on a LG heat pump: Communication error between inverter PCB (outdoor) and Main PCB (outdoor cycle)
Short answer
On a LG heat pump, CH52 means: Communication error between inverter PCB (outdoor) and Main PCB (outdoor cycle). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Communication error between inverter PCB (outdoor) and Main PCB (outdoor cycle).
Part involved: outdoor PCBs / harness.
When it shows: Main PCB(Outdoor cycle) fails to receive inverter PCB signal.
Likely causes:
- Communication line connection or harness failure; standby power control unit burnout; inverter PCB damaged; noise.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: no.
Manual reset: Service-engineer repair and restart required (LG: resumed only after certificated professional's check).
What you can check
- Read the code on the controller (LG shows 'CH' + number; older wired controllers alternate 'CH' and the number) and note it together with the model number. Report it to your installer or an LG-authorised service centre – LG owner's manuals say an error code generated by self-diagnosis is a reason to call the service. This is an 'Error'-class fault: LG says the system can only be resumed after a qualified professional has checked it, so do not keep trying to restart it. Check (without opening any panels) that the outdoor unit is not blocked by leaves, debris, snow or ice and that nothing is stacked against the coil or fan grille.
What the engineer will check
- Check the communication cable terminations and polarity between the named PCBs, look for intermediate twisted joints, shorts or open circuits, check for noise sources near the cable, confirm supply voltage and earthing, check software/EEPROM versions of both PCBs are compatible, then replace the defective PCB. Check communication LEDs (yellow) blinking on both outdoor PCBs and 5 V on Main PCB.
Who to ask for: Heat pump engineer / electrician (inverter and PCB diagnostics).
Certification: Competent person for electrical work (BS 7671); isolate and wait 3 min for DC-link discharge.
What you might notice
Sources
- AIR-TO-WATER HEAT PUMP SERVICE MANUAL (General) – R32 Hydrosplit, MFL68682007 ↗ · MFL68682007 · page 72, 117 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026