Air Conditioner
LG
Updated Jul 24, 2026
LG AC CH02 Error — Indoor Pipe Sensor Fault & How to Fix It
CH02
LG · Air ConditionerCH02 on an LG AC means the indoor pipe (evaporator) temperature sensor has an open or shor…
Quick answer
CH02 on an LG AC means the indoor pipe (evaporator) temperature sensor has an open or short circuit. The unit cannot monitor coil temperature.
What CH02 means
The indoor pipe sensor is a thermistor clamped directly onto the evaporator coil copper pipe. It tells the control board how cold the coil is getting, so the board can prevent ice buildup (freeze protection) and manage compressor speed.
When the sensor wire breaks or the thermistor itself fails, the board sees an impossible reading — either infinite resistance (open) or near-zero (short) — and raises CH02. The compressor stops, though the indoor fan may continue running.
Do not keep restarting. Without pipe-temperature feedback the evaporator can freeze solid, and running a frozen coil damages the compressor.
How to fix it
The pipe sensor is inside the indoor unit, clipped to the evaporator. Accessing it requires removing the front panel and sometimes the filter frame.
- Isolate power at the breaker.
- Open the indoor unit and locate the pipe sensor — a small probe clipped to one of the copper U-bends on the evaporator.
- Check the connector at the PCB. Reseat it firmly.
- Measure resistance. At 25 °C, the LG pipe thermistor typically reads about 5 kOhm (note: different from the 10 kOhm room sensor). An open or zero reading means the sensor is dead.
- Replace if needed. Unclip the old sensor, clip the new one firmly onto the pipe (good thermal contact is essential), and plug it in.
- Restore power and run the AC. Confirm CH02 is gone and the coil cools evenly.
What does the CH02 code mean?
CH02 indicates the indoor evaporator pipe temperature sensor (thermistor) has an open or short circuit. The board cannot monitor coil temperature for freeze protection.
Common causes
- Faulty pipe thermistor (most common)
- Loose connector on the indoor PCB
- Sensor displaced from the pipe (not making thermal contact)
- Wiring damage between sensor and board
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How to fix the CH02 error
Isolate power
Switch off at the breaker and wait one minute.
Open the indoor unit
Remove the front panel to access the evaporator.
Locate the pipe sensor
A thermistor probe clipped to the evaporator copper pipe, connected via two wires to the PCB.
Reseat the connector
Unplug and re-plug firmly at the PCB.
Measure resistance
Expect about 5 kOhm at 25 degrees C for LG pipe sensors. Replace if open or zero.
Ensure good contact
The sensor must be firmly clipped to the pipe. Poor contact gives inaccurate readings.
Restore power and test
Run the AC and confirm CH02 clears and the coil cools evenly.
Safety first: Evaporator fins are sharp — wear gloves. If the coil is frosted over, let it defrost completely before working on the sensor.
Part you may need: Indoor pipe temperature sensor (NTC 5 kOhm thermistor)
LG pipe sensors and room sensors have different resistance values. Do not swap them.
Frequently asked questions
What is the difference between CH01 and CH02?
CH01 is the room (air) sensor; CH02 is the pipe (coil) sensor. Different parts, different resistance values, but the diagnostic process is similar.
Can a frozen coil trigger CH02?
A frozen coil itself does not cause CH02, but a faulty CH02 sensor can allow the coil to freeze because the board has no freeze-protection data.
✎ Written by
REZAUL Karim (Riad)
REZAUL Karim (Riad) is the founder of ErrFixHub and a hands-on electronics and home-appliance repair specialist with over 15 years of experience diagnosing and fixing air conditioners, washing machines, refrigerators, inverters and other household appliances. He built ErrFixHub to turn cryptic error codes into clear, step-by-step fixes anyone can follow — cross-checking every code against manufacturer documentation and real repair-bench experience.
