CH09 on a LG heat pump: Indoor PCB program (EEPROM) fault – optional EEPROM loosely inserted, removed, burnt, or data mismatched
Short answer
On a LG heat pump, CH09 means: Indoor PCB program (EEPROM) fault – optional EEPROM loosely inserted, removed, burnt, or data mismatched. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the LG, all models
The manual says: Indoor PCB program (EEPROM) fault – optional EEPROM loosely inserted, removed, burnt, or data mismatched.
Part involved: indoor Main PCB EEPROM / option PCB.
When it shows: EEPROM check fails at start-up.
Likely causes:
- Optional EEPROM loosely inserted or removed; EEPROM burnout/electrical or mechanical damage; EEPROM value and program value not matched.
On the THERMA V Water Heater (heat pump DHW cylinder)
The manual says: EEPROM error (THERMA V water heater).
Part involved: PCB / controls.
When it shows: EEPROM error.
Likely causes:
- EEPROM error.
Is it safe?
On the LG, all models
| 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).
On the THERMA V Water Heater (heat pump DHW cylinder)
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: unknown.
Manual reset: Per LG corrective action; service engineer for most codes.
What you can check
On the LG, all models
- 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.
On the THERMA V Water Heater (heat pump DHW cylinder)
- Note the code shown on the water heater display. LG's corrective action: call LG technical support. While the fault is present the unit operates as: Use elements only – hot water will be heated more slowly/at higher cost.
What the engineer will check
On the LG, all models
- Check option PCB is plugged into indoor Main PCB, EEPROM insertion direction (groove) and condition; replace EEPROM or indoor Main PCB; LG R290 installer manual: request support from LG.
Who to ask for: Heat pump engineer (controls, sensors, PCB).
Certification: None statutory beyond electrical competence (BS 7671).
On the THERMA V Water Heater (heat pump DHW cylinder)
- Check PCB connections/communication and anode (ICCP) circuit; replace PCB/anode controller as required.
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 71, 84 · Reviewed 23 September 2026
- LG Heat Pump Water Heater Owner's Manual WH20S F5 / WH27S F5 (EU/UK multilingual), MFL71409209 Rev.00 (2023) – ManualsLib 3195149 ↗ · MFL71409209 Rev.00_090823 · page 32 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026