CH117 on a LG THERMA V R290 Monobloc: Condenser in-pipe temperature sensor error (open/short) – thermistor not inserted or inserted incorrectly (R290)
Short answer
On a LG heat pump, CH117 means: Condenser in-pipe temperature sensor error (open/short) – thermistor not inserted or inserted incorrectly (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: Condenser in-pipe temperature sensor error (open/short) – thermistor not inserted or inserted incorrectly (R290).
Part involved: condenser inlet pipe thermistor.
When it shows: Sensor open/short.
Likely causes:
- Thermistor missing/mis-inserted; connector/sensor defect; outdoor PCB defect.
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 thermistor is fully inserted in its pocket/holder and the connector is seated on the correct PCB header; measure resistance unplugged (LG: pipe/water sensors 5 kΩ at 25 °C, room air sensor 10 kΩ at 25 °C, D-pipe sensor ~200 kΩ at 25 °C) and voltage plugged (~2.2–2.5 V DC at 25 °C) against LG resistance-temperature tables; replace sensor, then PCB if readings are correct.
Who to ask for: Heat pump engineer (controls, sensors, PCB).
Certification: None statutory beyond electrical competence (BS 7671).
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, 87 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026