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Error code reference

LG Hvac Error Code CH01

Indoor thermistor open or short circuit error, causing operation to turn off.

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Indoor thermistor open or short circuit error, causing operation to turn off.

First step from the service manual

Check the connection of circuit connector and lead line connecting connector.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What CH01 means on a LG hvac

The CH01 error code on an LG HVAC system indicates that the indoor unit thermistor has experienced an open or short circuit condition. The indoor thermistor is a temperature-sensing resistor responsible for monitoring the return air or coil temperature inside the air handler or indoor unit. The system control board continuously reads the resistance value from this thermistor to regulate compressor operation, fan speed, and overall system performance. When the resistance reading falls outside the expected range due to an open or short circuit, the control board interprets this as a sensor fault and shuts down operation to prevent damage from uncontrolled temperature conditions.

An open circuit means the electrical path through the thermistor has been broken, producing an infinite or unmeasurably high resistance reading. A short circuit means the thermistor leads or wiring have made unintended contact, producing a near-zero resistance reading. Both conditions give the control board an implausible temperature value, triggering the CH01 fault and halting system operation.

The first diagnostic step is to inspect the circuit connector and the lead line connecting connector between the thermistor and the control board. Loose, corroded, or physically damaged connectors are a frequent cause of intermittent or permanent signal loss. If the connectors appear intact and secure, the thermistor itself should be tested for proper resistance values at a known ambient temperature. A failed thermistor or damaged wiring harness will require component replacement to restore normal operation.

Source: manufacturer service documentation.

Common causes of CH01

  1. 01

    Loose or disconnected wiring connector

    Wiring / connection

    The connector linking the thermistor lead line to the control board can work loose over time due to vibration or handling during maintenance. This is the first thing to check, as reseating a loose connector often resolves the fault without any parts replacement.

  2. 02

    Failed indoor thermistor

    Part replacement

    The thermistor itself can fail internally, developing an open or short circuit that produces an out-of-range resistance value. Testing the thermistor with a multimeter at a known temperature will confirm whether it has failed and needs replacement.

  3. 03

    Damaged thermistor lead wire

    Part replacement

    The wire running from the thermistor to the connector can become pinched, cut, or abraded, breaking the circuit or creating an unintended short. Inspect the full length of the lead wire for visible damage, kinks, or contact with sharp edges.

  4. 04

    Corroded or contaminated connector

    Wiring / connection

    Moisture or debris inside the connector housing can corrode the terminals and increase resistance to the point where the control board reads the connection as open. Cleaning the connector contacts or replacing the connector may be necessary.

  5. 05

    Control board fault

    Part replacement

    In rare cases, the control board itself may misread the thermistor signal due to a failed input circuit on the board. This should only be considered after the thermistor and all wiring have been confirmed good.

See the test procedure for each cause

Frequently asked questions about CH01

What does CH01 mean on a LG hvac?
CH01 on an LG HVAC system means the indoor thermistor has an open or short circuit condition. The thermistor is the temperature sensor inside the indoor unit that the control board uses to regulate system operation. Because the sensor is producing an invalid reading, the system shuts down automatically. The fault must be resolved before the unit will resume normal operation.
Can I fix the CH01 error myself?
A homeowner with basic comfort can check whether the thermistor wiring connector has become loose and reseat it, which sometimes clears the error. However, testing the thermistor resistance and inspecting internal wiring requires opening the unit and using a multimeter, which is better suited to an experienced DIYer or technician. If the thermistor itself has failed, replacing it requires identifying the correct part for your specific model.
Is it safe to keep using my LG unit while CH01 is displayed?
No. When CH01 is active, the LG system turns off operation automatically because it cannot reliably monitor indoor temperatures. Attempting to bypass this safety shutoff and run the system without a functioning thermistor could result in uncontrolled operation and potential damage to system components. The fault should be diagnosed and corrected before resuming use.
Will resetting the unit clear the CH01 code?
A power reset may temporarily clear the CH01 code if the fault was caused by a momentary connector interruption, but if the thermistor or wiring is genuinely faulty, the error will return once the system restarts and re-checks the sensor. Resetting without repairing the underlying cause is not a reliable fix. The connector and thermistor should be inspected regardless of whether a reset appears to work.
How much does it cost to repair a CH01 error on an LG HVAC system?
Repair costs depend on the root cause. If a loose connector is the issue, a service call to diagnose and reseat the connection typically runs in the range of $75 to $150 for labor. If the thermistor itself needs replacement, parts can add $20 to $80 depending on the model, plus labor. A damaged wiring harness or control board failure would increase costs further, potentially ranging from $150 to $400 or more including parts and labor.

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