CH06 on a LG heat pump: Problem in refrigerant outlet (gas) side pipe temperature sensor of indoor unit – open or short
Short answer
On a LG heat pump, CH06 means: Problem in refrigerant outlet (gas) side pipe temperature sensor of indoor unit – open or short. The heat pump keeps running with some functions stopped. 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: Problem in refrigerant outlet (gas) side pipe temperature sensor of indoor unit – open or short.
Part involved: refrigerant outlet (gas) pipe thermistor.
When it shows: Sensor open/short (5 kΩ at 25 °C unplugged, 2.5 V DC plugged).
Likely causes:
- Incorrect connection between sensor and PCB; PCB fault; sensor fault.
On the THERMA V Water Heater (heat pump DHW cylinder)
The manual says: Lower tank temperature sensor is not working (THERMA V water heater).
Part involved: thermistor.
When it shows: Lower tank temperature sensor is not working.
Likely causes:
- Lower tank temperature sensor is not working.
Is it safe?
On the LG, all models
| 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.
On the THERMA V Water Heater (heat pump DHW cylinder)
| 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: 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. 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.
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: OFF – no hot water from this unit.
What the engineer will check
On the LG, all models
- 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).
On the THERMA V Water Heater (heat pump DHW cylinder)
- 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 / 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 · 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