LG Mini Split CH01 Error Code — What It Means
LG error code CH01 (also displayed as “C1” or “CH 01”) means the indoor unit room temperature sensor has failed or is reading an out-of-range value. The indoor PCB reads the thermistor resistance at startup and continuously during operation. When the resistance falls outside the expected range — either open circuit, short circuit, or a value that corresponds to an implausible temperature — the board shuts down and displays CH01. This protects the system from running in a mode where it can’t properly regulate temperature. The fix is almost always a simple sensor replacement.
Common Causes
- Failed indoor room temperature thermistor — The thermistor is a small NTC (negative temperature coefficient) bead on a wire harness, located behind the front panel near the return air intake. These sensors fail open or short with age and exposure to condensation.
- Loose or corroded thermistor connector — The thermistor plugs into the indoor PCB with a small 2-pin connector. Corrosion or a partially seated connector produces an out-of-range reading that triggers CH01.
- Short to ground or damaged wire — The thermistor lead wire (typically 3–5 inches long) can chafe against a sharp edge inside the unit casing and short to the chassis.
- Failed indoor PCB — Rare, but if the thermistor tests in-spec but CH01 persists, the PCB input circuit for the sensor may have failed.
Step-by-Step Fix
- Power off and access the sensor — Shut off the unit and remove the front panel and filter. The room temperature sensor is typically a small bead on a wire, clipped to the evaporator coil frame or mounted in an air intake slot.
- Test the thermistor — Disconnect the sensor from the PCB. Using a multimeter set to resistance (ohms), measure across the two sensor leads. At room temperature (70°F/21°C), a typical LG thermistor reads approximately 10–15 kΩ. An open (infinite resistance) or shorted (near 0) reading means replace it.
- Check the connector — Even if the sensor reads in-spec, clean the 2-pin connector contacts with electrical contact cleaner. Re-seat firmly and test.
- Inspect the lead wire — Follow the wire from the sensor to the PCB connector. Look for any point where it contacts sharp metal or could be pinched.
- Reset the system — Restore power after installing a new sensor or reseating the connector. CH01 should clear immediately if the sensor now reads in-range.
Parts Often Needed
| Part | Notes |
|---|---|
| LG indoor thermistor (room temp) | LG part 6615A20042A or equivalent; confirm for your model series |
| Contact cleaner | For connector maintenance |
| Indoor PCB | If sensor tests good and fault persists |
Need Replacement Parts?
Finding the right replacement parts for your equipment is critical to getting it running again. Check current prices on Amazon — prices and availability change frequently.
When to Call a Pro
If you’ve replaced the sensor and the fault persists, the PCB input circuit is suspect. LG service tools can read live thermistor values directly; an authorized LG tech can confirm board vs. sensor without guesswork.