LG Aircon CH31 Error Code & Blinking Light
Use this LG CH31 guide to decide when to stop resetting, what to capture, and what to check before parts are quoted. Match the model first; same-looking signals can point to different rows.
What Does LG CH31 Mean?
LG CH31 is listed as current-to-current transformer thermistor is too low and current to the current-transformer thermistor too low in Wall-Mounted Split rows such as HSV4 / HSV5 single-zone wall-mounted systems, LS091HSV / LS121HSV wall-mounted single-zone. The loaded row is source-backed by official diagnostic material. Do not collapse this code across model families; use the model, series, or system type to choose the right row. Confirm the exact model, series, or signal row before accepting a parts quote.
Open, shorted, displaced, or out-of-range thermistor or pressure-sensor reading.
Loose sensor connector, damaged sensor harness, or water-affected wiring.
PCB input fault after the sensor and wiring readings are confirmed.
What To Do Now
Use these steps before another reset, sensor check, or PCB quote.
Stop using the unit if CH31 returns
If CH31 returns after one reset, stop repeated restarts and get the matching source row diagnosed.
Reset CH31 once
Capture the CH31 pattern first, then power-cycle once only and note whether the same fault returns.
Send these to us
CH31 error code and blinking light, a clear display photo and blinking-light video if the unit shows one, LG model stickers, affected rooms, reset result, and when the fault appears
Send Us What You're Seeing
Share CH31, your LG model, and what happened before it appeared. We'll read it and respond with the right next step before any work is approved.
What To Check Before Repair
Use this split to separate safe evidence capture from the tests a technician should prove before quoting parts.
| You Can Check | Technician Should Confirm |
|---|---|
| Before resetting CH31, take a clear display photo and blinking-light video if the unit shows one. | Confirm which sensor CH31 maps to on the exact model table. |
| Capture the LG indoor and outdoor model stickers so the correct family row is used. | Measure the sensor value against the service-manual resistance or voltage range. |
| Note whether one room, several rooms, or the whole system is affected, plus whether it returns after one reset. | Check connector condition, harness continuity, and PCB input before replacing boards. |
What Changes The Next Step
These clues decide whether the first check is room-side, shared outdoor-side, refrigerant-side, source-table, or model-family confirmation.
| What You See | What It Points To |
|---|---|
| Only one indoor unit shows CH31. | The affected room, indoor board path, wiring route, or local component should be checked first. |
| Several rooms or the outdoor unit show the same CH31 fault. | The shared outdoor side, power path, communication trunk, or refrigerant circuit needs priority checking. |
| The fault appears immediately even before the unit cools properly. | Sensor value, connector, harness, and PCB input should be tested in that order. |
| The same code appears with different meanings in the source rows. | Model family, source table, and system type decide which meaning applies before parts are quoted. |
| The model belongs to Wall-Mounted Split rows such as HSV4 / HSV5 single-zone wall-mounted systems, LS091HSV / LS121HSV wall-mounted single-zone. | The loaded row is source-backed by official diagnostic material. Use the matching source row before quoting parts. |
Sensor Or PCB Decision
LG CH31 is usually repair-first if a sensor or harness reading is confirmed. Board replacement should wait until the sensor circuit is tested.
Sensor replacement is usually targeted when resistance or voltage readings are out of range.
Harness or connector damage can look like a sensor fault until continuity is checked.
PCB replacement is a later step if the sensor and wiring test correctly.
Read Next
Use these if the quote mentions the parts, checks, or repair path this code points to.
Other LG Error Codes
If the code you're seeing isn't CH31, jump to one of these or browse the full LG list.
Ready to Get Started?
Send the CH31 error code and blinking light, a clear display photo and blinking-light video if the unit shows one, and LG model sticker. Send the model sticker so the matching official row can be checked quickly. We can help separate sensor, harness, and PCB-input checks.