LG air conditioning systems use an intelligent diagnostic system denoted by “CH” error codes or corresponding blinking LED flash patterns on the indoor fan coil unit and outdoor condenser board. When an operational anomaly or hardware failure happens, the unit restricts operation to protect components. Knowing how to interpret these error codes helps you understand whether the issue calls for a simple reset or immediate professional care.
1. Error Code Category Overview
LG error codes and LED indicators are systematically split into specific operational categories:
- CH01 – CH04 (Indoor Sensor & Pump Faults): Covers room thermistors, pipe sensors, and indoor condensate drainage pumps.
- CH05 – CH09 (Communication & Memory Errors): Identifies inter-unit wiring breakdowns or indoor EEPROM data corruptions.
- CH10 – CH12 (Indoor Mechanical Failures): Covers indoor blower motor locks and main control board anomalies.
- CH21 – CH33 (Inverter & Power Protection Trips): Signals IPM module spikes, current transformer overloads, or compressor discharge overheating.
- CH34 – CH38 (Pressure & Refrigerant Anomalies): Flags high/low pressure switch trips and refrigerant circuit imbalances.
2. Step-by-Step Display Reading & Reset Guide
Follow these steps to safely check and reset your LG aircon system:
- Check the Display or Blinking Lights: Look for a digital error code (e.g.,
CH05,CH34) on your indoor panel, wired controller, or the LG ThinQ app. If your unit only has indicator lights, count the blinking sequence of the operation and timer LEDs (e.g., 2 slow blinks and 1 fast blink translates to CH21). - Do Not Force Immediate Restarts: Avoid repeatedly turning a tripping unit back on, as this can worsen electrical faults.
- Power Off at the Wall Switch/Breaker: Turn off the air conditioner via the remote, then switch off the main wall isolator or circuit breaker.
- Wait 5 Minutes: Let the system sit completely unpowered for 5 minutes to drain residual voltage and reset the system memory.
- Reboot and Test: Switch the breaker back on and restart the cooling system. If the error code returns immediately, a physical hardware problem exists.
3. Comprehensive LG Error Code Reference Table
| Code / LED Signal | Meaning / Possible Cause | Severity | Recommended Action | Typical Repair Cost (SGD) |
| CH01 (E2) | Indoor room temperature sensor open/short | 🟡 Medium | Check sensor wiring harness connector on indoor PCB; replace thermistor. | From $130 |
| CH02 (E1) | Indoor pipe/coil temperature sensor fault | 🟡 Medium | Inspect evaporator coil thermistor connection; replace if defective. | From $130 |
| CH03 (E4) | Condensate drain pump or high-level float switch error | 🟡 Medium | Clear blocked drain pipes/pan; test or replace the internal drain pump. | From $90 |
| CH05 (E5) | Indoor and outdoor unit communication failure | 🔴 High | Inspect inter-unit control cables for loose screw terminals or damage. | $80 – $300 |
| CH09 | Indoor unit EEPROM / memory checksum error | 🔴 High | Perform hard reset; if error persists, replace the indoor control PCB. | $250 – $450 |
| CH10 (C1) | Indoor fan motor lock or rotation failure | 🔴 High | Clear physical debris from blower wheel; test or replace indoor fan motor. | $200 – $350 |
| CH21 | Outdoor DC compressor IPM (Inverter Module) fault | 🔴 High | Professional electronic diagnosis required; replace outdoor inverter PCB. | $300 – $600 |
| CH23 | Outdoor DC compressor overcurrent spike | 🔴 High | Check power supply stability, compressor windings, and refrigerant load. | From $180 |
| CH26 | Inverter compressor seized or not rotating | 🔴 High | Inspect compressor electrical status and inverter drive circuitry. | From $750 |
| CH32 | Outdoor discharge pipe temperature too high | 🔴 High | Clean dirty outdoor condenser coils or check for low refrigerant gas. | From $180 |
| CH34 | High pressure safety switch activated | 🔴 High | Clear blocked outdoor airflow or correct overcharged refrigerant levels. | From $180 |
| CH35 | Low pressure safety switch activated (Gas leak) | 🔴 High | Perform nitrogen pressure test, locate and seal leak, then vacuum-recharge gas. | From $180 |
4. DIY vs. Professional Repair Matrix
🟢 Safe to DIY
- Mesh Filter Cleaning: Washing and drying indoor dust filters every 2 weeks to prevent airflow restriction.
- Drain Maintenance: Clearing basic slime or blockages from the condensate discharge pipe (addressing CH03).
- Hard Reset: Executing a standard 5-minute wall breaker power cycle to clear temporary electronic glitches.
🔴 Requires Professional Repair
- Refrigerant Line Services: Pressure-testing piping, repairing gas leaks, and vacuum-recharging refrigerant (CH35).
- Electronic Board & Inverter Swaps: Replacing damaged indoor/outdoor control PCBs or IPM inverter modules (CH09, CH21).
- Mechanical Part Replacements: Swapping out seized blower motors, thermistors, or high-pressure switches (CH10, CH34).
🚨 CRITICAL SAFETY WARNING: High-severity error codes like CH21, CH26, CH34, and CH35 indicate serious risks involving electrical overloads, high system pressures, or refrigerant depletion. Forcing the aircon to keep running under these conditions can permanently damage the compressor. Switch off the unit at the main isolator immediately.
Contact & Professional Services
For expert error code diagnosis, chemical cleaning, or aircon repair services across Singapore, reach out to our team today:
- Company Name: Aircon Servicing & Repair Singapore
- Address: 269 Bukit Batok East Ave 4, Singapore 650269
- Phone Number: +65 9855 3721
