CH145 on a LG THERMA V R290 Monobloc: Communication error between Sub PCB (outdoor) and Main PCB (outdoor cycle) – R290
Short answer
On a LG heat pump, CH145 means: Communication error between Sub PCB (outdoor) and Main PCB (outdoor cycle) – R290. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Communication error between Sub PCB (outdoor) and Main PCB (outdoor cycle) – R290.
Part involved: outdoor Sub PCB (hydraulic sensors, pump) / harness.
When it shows: Main PCB(Outdoor cycle) fails to receive Sub PCB signal.
Likely causes:
- Communication line connection failure; harness failure; standby power control unit burnout.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: yes – trouble clears when the condition is repaired; emergency operation must be restarted by the user after a power reset.
Manual reset: Not normally required; user restarts after power reset if emergency operation was running.
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. For this 'trouble' class LG allows temporary emergency operation: if the controller shows a pop-up offering it you may accept (OK) as a stop-gap; running costs will be higher, so do not use it long term. Emergency operation does not restart by itself after a power cut – you must switch it back on at the controller.
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.
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
What owners and engineers report
1 owner and engineer report mentions this.
- No heating on the THERMA V R290 Monobloc: 1 report
Sources
- LG THERMA V R290 Monobloc Trouble Shooting Guide (FHNW16606C0 / HM..HF UB60/UB40) – ManualsLib 4570773 ↗ · © 2023-2024 (revision not printed on viewed pages) · page 64, 95 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026