LG CH01 Error Code: Indoor return air thermistor fault
Updated October 2026 · Sourced from LG documentation
🛑 Turn it off and call a licensed pro
The indoor unit return air thermistor (temperature sensor) has disconnected or has shorted out.
Is it safe to keep running? No. Turn it off and get it checked. A technician needs to check the sensor and its connection.
CH01 at a glance
| Code / how it shows | Meaning | Applies to |
|---|---|---|
| CH01 Also: 1 On North American units, shown as blinking indicator LEDs (indoor unit, LED1 1 blink); on other markets shown as the number 1 | Indoor return air thermistor fault | LG single-split and multi-split air conditioners (North America LED blink code chart) |
Check this first
Only steps a homeowner can do safely. Do not open electrical panels or the burner area.
- Turn the power off or trip the circuit breaker for the unit, wait about 5 minutes, then turn it back on.
🛑 Stop and call a licensed pro if
- A technician needs to check the sensor and its connection.
- Any code pointing to refrigerant, the compressor, high pressure or the outdoor unit board. Refrigerant work legally needs a certified technician.
- Burning smell, sparks, or a breaker that trips again after a reset.
- Water leaking from the indoor unit that does not stop after the drain is clear.
Safe first steps for any LG code
- Write down the exact code and how it shows (remote display or number of lamp blinks). Similar codes mean different things on different series.
- Turn the system off at the remote, switch off the breaker or disconnect for the unit, wait a few minutes, then turn it back on.
- Clean or replace the indoor unit air filters, and make sure nothing blocks the indoor or outdoor unit.
- Check that the condensate drain line is not blocked or kinked where you can see it.
- Replace the remote controller batteries if the display is dim or the unit does not respond.
Source: LG Single / Multi-Split Air Conditioner Error Codes (LG Canada help library), Error Code Chart. Codes are series-specific, so your unit's own manual is the final word. Reviewed October 2026.
Shaun Cain · Certified HVAC & Refrigeration Technician · Ask an HVAC technician
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