LG AC Error Codes: What Each Code Means and How to Fix It
LG air conditioners use CH (Check) codes to report faults. These codes appear on the indoor unit display and in the LG ThinQ app if your AC is connected. This guide covers every common LG AC error code — the cause and the fix you should try before calling a technician.
LG AC Error Code Table
| Code | Meaning | Fix |
|---|---|---|
| CH01 | Indoor room temperature sensor fault | Check sensor connector; replace sensor if faulty |
| CH02 | Indoor pipe temperature sensor fault | Inspect sensor connection on PCB; replace if needed |
| CH03 | Outdoor temperature sensor fault | Check outdoor unit sensor; replace sensor |
| CH05 | Communication error (indoor–outdoor) | Power cycle both units; check signal wiring |
| CH10 | Indoor fan motor fault | Check fan blade for obstruction; replace motor if needed |
| CH21 | High-pressure protection | Clean condenser coil; check for refrigerant overcharge |
| CH22 | Low-pressure protection | Check for refrigerant leak; call technician for gas top-up |
| CH38 | Outdoor unit current protection / compressor overload | Turn off AC; check power supply and compressor wiring |
| CH67 | Outdoor unit PCB fault | Power cycle unit; PCB may need replacement |
| CH25 | Discharge temperature too high | Check for blocked airflow; clean condenser fins |
| CH47 | Low temperature protection (heat mode) | Normal in very cold weather; wait for outdoor temp to rise |
Top LG AC Error Codes Explained in Detail
CH05 — Communication Error
CH05 is LG’s equivalent of a communication breakdown between the indoor and outdoor units. This often happens after a power cut or voltage fluctuation. Turn both units off at the breaker for 2 minutes, then restart. If CH05 returns, a technician needs to inspect the inter-unit signal cable — it may be damaged or have a loose terminal connection.
CH21 — High Pressure Protection
This code appears when the refrigerant pressure on the high side is too high. A dirty condenser coil on the outdoor unit is the most common cause — blocked fins prevent heat rejection, causing pressure to spike. Turn off the AC and clean the outdoor unit fins. If the coil is clean, refrigerant may be overcharged — a technician needs to check system pressure.
CH22 — Low Pressure Protection
CH22 typically indicates low refrigerant due to a leak. Look for ice forming on the indoor unit’s copper pipe — a strong sign of low gas. Stop running the AC immediately. A certified technician must locate the leak, fix it, and recharge the system.
CH38 — Compressor Overload
CH38 is a serious code indicating the outdoor unit’s compressor is drawing excessive current. This can be caused by a failing compressor, a wiring fault, or the AC running in very high ambient temperatures. Power off the AC and do not restart until a technician has inspected the compressor.
How to Reset an LG AC After an Error
- Press the power button to turn off the AC.
- Disconnect power at the main switch or breaker.
- Wait 3 minutes.
- Restore power and turn the AC on.
- If the CH code reappears, the fault is persistent and needs a service visit.
When to Call a Technician
- CH22 low-pressure or CH21 high-pressure errors — refrigerant system issue.
- CH38 or any compressor protection code.
- CH67 outdoor PCB fault — component failure.
- Error persists after a full power reset.
Also useful: How to Sell Your Old AC in Mumbai and How to Sell Your Old AC in Chennai if repeated errors mean it is time to replace your unit.