CH231 on a LG heat pump: Problem in water pressure sensor – sensor damaged or incorrectly connected
Short answer
On a LG heat pump, CH231 means: Problem in water pressure sensor – sensor damaged or incorrectly connected. 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: Problem in water pressure sensor – sensor damaged or incorrectly connected.
Part involved: water pressure sensor (CN_H20_PRESS).
When it shows: Sensor voltage abnormal (normal 0.65 V at 1.0 bar; 0.53-0.95 V for 0.2-3.0 bar).
Likely causes:
- Incorrect connection between sensor and PCB (indoor Main PCB, or outdoor Sub PCB on R290); PCB fault; sensor fault.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
| 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. Look at the system pressure gauge and tell the engineer what it reads (LG commissioning guidance is roughly 1.5–2.5 bar when cold); do not top up or bleed the system yourself unless your installer has shown you how, and make sure any filling loop is closed.
What the engineer will check
- Check displayed pressure against the mechanical gauge; check connector and sensor voltage table; replace sensor then PCB.
Who to ask for: Heat pump engineer (controls, sensors, PCB).
Certification: None statutory beyond electrical competence (BS 7671).
What you might notice
Sources
- AIR-TO-WATER HEAT PUMP SERVICE MANUAL (General) – R32 Hydrosplit, MFL68682007 ↗ · MFL68682007 · page 71, 77-79 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026