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LG S18ET NSJ Dualcool Smart: CH05 and CH06 Error Diagnosis
📋 AI-generated diagnosis based on technical documentation Generated by ReeFix AI · Sources: technical and specialist documentation (see Sources section) Revision of 09/08/2026
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⚠️ SAFETY WARNING / SERIOUS RISK. This appliance operates with critically dangerous components (High Voltage or Gas). DIY repair of critical devices can be fatal and is prohibited by law. Physical intervention legally requires qualified specialized technicians to issue compliant safety certificates. ReeFix provides this diagnosis EXCLUSIVELY for educational and informational purposes.
CH05 (communication error between indoor and outdoor units) and CH06 (NTC heat exchanger sensor anomaly of the indoor unit) errors on LG Dualcool Smart (S18ET NSJ) are closely related. The most probable cause (55-60%) for both is a fault or thermal drift of an NTC sensor for the indoor unit heat exchanger of an LG Dualcool Smart (S18ET NSJ). A blockage due to the CH06 code can indeed interrupt correct serial communication, generating the CH05 code in cascade.
When the CH06 error occurs, the LG air conditioner suddenly stops and often shows six consecutive flashes on the split's LED. This behavior indicates that the sensor no longer correctly detects the evaporator temperature, preventing the air conditioning cycle from starting for safety.
Less probable is a problem with the interconnection wiring between the two units (25-30%) or a fault in the external electronic board for LG Dualcool Smart (S18ET NSJ) (10-15%). Prolonged exposure to humidity and temperature fluctuations often deteriorates sensors or oxidizes wiring contacts. A professional Fluke digital multimeter is essential for measuring sensor resistance and verifying communication voltage on the serial line.
Operational decision: For your safety and the complexity of the intervention, which involves mains voltages and refrigerant gases, always contact a qualified technician. DIY is discouraged and potentially dangerous. Replacing the entire air conditioner is rarely necessary for these codes, as repair by replacing the sensor or restoring the wiring is highly cost-effective and efficient.
Frequently Asked Questions
Why does my LG Dualcool Smart S18ET NSJ show CH05 and CH06 errors?
CH05 and CH06 errors on LG Dualcool Smart S18ET NSJ are related: the internal unit's NTC sensor failure (CH06) blocks communication (CH05).
What are the less common causes of CH05 and CH06 errors on LG Dualcool Smart?
Less likely are problems with the interconnection wiring (25-30%) or a failure of the outdoor electronic board (10-15%).
When should I call a technician for CH05 and CH06 errors on my LG air conditioner?
Due to high voltages and refrigerant gases, it is legally mandatory to contact a qualified technician for any physical intervention.
ℹ️ This video shows a different model. The diagnostic technique illustrated is applicable to this device as well.
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⭐ Verified ReeFix Partners
This diagnostic report is generated using an artificial intelligence system (RAG) based on the aggregation of online data. The moderation by Luca Chia (Electronic Expert) validates its logical coherence and technical plausibility regarding the described symptoms, confirming the correctness of the AI's diagnostic reasoning, without however constituting an absolute guarantee of resolution for individual cases.
