Compressor Discharge Sensor
LG CH41 Error Code
The LG CH41 error code appears when the outdoor unit can no longer read the temperature sensor fitted to the compressor discharge pipe. That reading guards the compressor against overheating, so the unit stops until the sensor works again. This page walks through what the sensor does, why it fails, and how it gets fixed.
Explained Simply
What Is the LG CH41 Code About?
When your compressor squeezes refrigerant gas, the gas leaves it very hot. It travels out through a short copper pipe called the discharge line, heading for the outdoor coil. LG fits a temperature sensor to that discharge pipe, close to the compressor, so the board always knows how hot the compressor is running.
CH41 means the outdoor board is reading a value from that sensor that cannot be right. LG service information describes it as the inverter compressor discharge pipe thermistor being open or short circuited. The sensor has either lost its connection or its resistance has collapsed.
This is a sensor fault code, not an overheating code. The compressor may be perfectly healthy. The problem is that the board has lost one of its most important protective readings, and it will not run the compressor blind.
That makes CH41 different from codes that describe high temperatures. If the discharge pipe were simply too hot, LG would use a different code. CH41 is about a missing or nonsensical reading.
Why It Matters
What Does the Discharge Sensor Protect?
The discharge temperature is one of the best indicators of how hard and how healthily the compressor is working. LG uses it for several jobs at once.
Overheat Protection
If discharge temperature climbs too high, the board slows or stops the compressor before its oil and windings are damaged.
Charge Monitoring
A low refrigerant charge makes discharge temperature rise. The board uses this reading as part of its low refrigerant detection.
Expansion Valve Control
On many LG inverters, the electronic expansion valve is adjusted partly based on discharge temperature, fine tuning refrigerant flow.
Because so many decisions rest on this one sensor, LG treats its loss as a reason to stop. Running without it would leave the compressor exposed to damage that the board could otherwise prevent.
Where to Look
How Does CH41 Show on an LG Unit?
The indoor display on LG splits with a number screen shows CH and 41. Units with lights only use a blink pattern, usually involving two lights to represent the two digits. Ducted and cassette systems display the code on the wired controller.
CH41 often appears soon after the system starts, because the board checks its sensors as part of the start up routine. If the fault is intermittent, perhaps caused by a lead that only loses contact when hot, the code may appear later in a run instead.
Unlike some outdoor faults, CH41 is not usually preceded by a change in performance. Cooling and heating tend to be normal right up until the code appears. That is a useful clue, as it separates a sensor fault from a developing refrigerant or compressor issue.
Open more detail
LG uses a cluster of codes in the forties for outdoor sensors. CH44 covers the outdoor air sensor, CH45 the condenser coil middle sensor, CH46 the suction line sensor and CH48 the coil outlet sensor on many models. Some third party lists also use CH47 for a discharge sensor on certain multi or commercial systems. The technician will confirm the exact meaning for your model before replacing a part.
Ranked Causes
What Causes an LG CH41 Fault?
The discharge sensor lives in one of the harshest spots in the whole system. It sits on a pipe that gets very hot, beside a compressor that vibrates, inside an outdoor unit exposed to the weather. Those conditions explain most failures.
Simple Causes
- A temporary electrical glitch, cleared by a full reset
- The sensor plug loosening on the outdoor board
- The sensor slipping out of its clip on the pipe
- Moisture reaching the plug during heavy rain
Repair Causes
- The thermistor failing after years of heat cycles
- Sensor lead insulation hardened and cracked by heat
- A lead worn through by vibration against a metal edge
- A fault in the sensor input on the outdoor board
Pests are also a factor in outdoor units. Insects, lizards and small rodents sometimes shelter inside the casing, and chewed sensor leads are a real cause of outdoor sensor codes. Ants are drawn to electrical components in some areas and can bridge contacts.
Owner Checks
Which Checks Are Safe to Try for CH41?
The discharge sensor is inside the outdoor unit, near the compressor and the inverter board. That area holds high voltages and very hot pipes. Keep your checks external.
- Take a photo of the code and note whether it appeared at start up or after running.
- Switch off at the remote and then at the breaker for at least five minutes.
- Walk around the outdoor unit and look for signs of animal activity, such as nests, droppings or chewed material near the base. Do not open panels.
- Check that rainwater is not pooling around the base of the unit or splashing into it from a gutter.
- Restore power and try once more in your usual mode.
If the code returns, switch off at the breaker and book a technician. If you saw signs of pests, mention this, as the technician may need to check other wiring as well.
Running It
Can I Keep Using My LG With a CH41 Code?
Most LG units will not run the compressor while CH41 is active, so cooling and heating stop. That is the system protecting itself, and it is the right outcome.
If your unit seems to keep running in a limited way, it is still best to switch it off. Without the discharge reading, the board cannot detect compressor overheating or a low refrigerant charge. If either of those problems developed while the sensor was out of action, the compressor could be damaged without warning.
CH41 by itself is not a costly fault in most cases. Keeping it that way means not running the system until the sensor is fixed.
Diagnosis Steps
How Does a Technician Repair an LG CH41 Fault?
The repair is usually straightforward, but it requires safe access to the inside of the outdoor unit. Here is the typical process.
Isolate and Wait
The technician isolates power at the outdoor unit and waits for the inverter board to discharge before removing covers.Locate the Sensor
They find the discharge thermistor on the pipe leaving the compressor and trace its lead back to the outdoor board.Inspect the Lead
The lead is checked for heat damage, cracking, chafing and pest damage along its full length.Measure Resistance
The thermistor resistance is measured and compared with the expected value at its current temperature. An open or short reading confirms failure.Check the Board Input
If the sensor tests correctly, the technician checks the board’s sensor input. A fault there points to a board repair.Replace and Refit Securely
A new sensor is fitted firmly to the discharge pipe, often with fresh thermal paste and insulation, and the lead is routed away from hot surfaces and sharp edges.Run and Verify
The system is run while the technician watches discharge readings rise and settle in a normal pattern.
Fitting Matters
Why Does Sensor Placement Matter So Much?
Discharge sensors must sit in firm thermal contact with the pipe. If a sensor is loose, it reads the air around the pipe instead of the pipe itself. The reading may not trigger CH41, but it will be wrong, and the board will make poor decisions about compressor protection and refrigerant flow.
A careful technician takes time over this detail. The sensor goes back in its correct clip or pocket, at the right point on the pipe, with any insulation sleeve refitted. The lead is tied back so vibration cannot rub it, and it is kept clear of the hottest parts of the compressor shell.
Poorly refitted sensors after earlier repairs are a known cause of repeat faults. If your LG has had outdoor work done before and CH41 has now appeared, mention it. The technician will pay close attention to how the sensor and lead were fitted.
Weather Factors
Can Australian Weather Contribute to CH41?
Heat is the main factor. On summer days, an outdoor unit in direct sun can get very hot inside its casing, adding to the heat already coming from the compressor. The discharge sensor and its lead endure higher temperatures than in milder climates, and the insulation on the lead can harden and crack faster.
Rain and humidity are the next concern. Outdoor units are designed to handle weather, but water from a faulty gutter or downpipe pouring directly onto a unit can find its way to connectors. Coastal homes face salt laden moisture, which corrodes sensor plugs and pins.
Storms can bring brief power disturbances that confuse sensor readings and cause a one off code. These usually clear with a reset. Dust from dry inland conditions can coat components and hold moisture against them, while bushfire smoke and ash can settle inside units in affected areas.
Care Tips
How Can I Protect the Discharge Sensor?
Owners cannot reach the discharge sensor, but they can keep its surroundings in good shape.
Shade Without Smothering
High shade over the outdoor unit lowers casing temperatures, as long as airflow around the unit is never blocked.
Fix Gutters and Downpipes
Make sure roof water does not pour onto the outdoor unit. Redirect any overflow away from it.
Discourage Pests
Keep the area around the unit tidy and free of food scraps, woodpiles and dense growth that shelter animals.
Regular servicing also helps. During a service, the technician can see whether sensor leads are sound and whether any pests have moved in.
Sensor or Something Else
How Is CH41 Different From an Overheating Problem?
Because the discharge sensor watches compressor heat, owners sometimes assume CH41 means the compressor is too hot. In fact, the two are reported differently, and knowing the difference helps you understand the urgency.
CH41: Sensor Fault
The reading is missing or impossible. The compressor may be perfectly fine. The fix is usually a sensor, its lead or its plug.
CH32: High Discharge Temperature
On many LG models, CH32 means the discharge temperature is genuinely too high. That points to a charge, airflow or compressor problem rather than a sensor fault.
If your unit has shown both codes over time, tell the technician. It may suggest the sensor is drifting, or that a real overheating problem has damaged the sensor.
What Happens When a Sensor Drifts Rather Than Fails?
Thermistors do not always fail cleanly. Some drift slowly, reading a little high or low for months before they finally open or short. During that period, the board receives readings that are wrong but still plausible, so no code appears.
A drifting discharge sensor can cause subtle symptoms. The compressor may slow down earlier than it should on hot days, reducing cooling. The expansion valve may not open to its best position, so efficiency falls. In some cases, the board may even suspect a low charge that does not exist.
When the technician replaces a failed discharge sensor, these subtle effects often disappear too. Owners sometimes notice the unit cools more strongly after the repair than it had for a while. That is a sign the old sensor had been giving misleading readings well before it triggered CH41.
For this reason, some technicians check the readings of neighbouring outdoor sensors while the unit is open. If the coil, suction or ambient sensors are of a similar age and showing odd values, it may be worth discussing them at the same visit. Replacing a part only when it tests faulty remains the rule, but spotting a drifting sensor early can save a second callout later in the season.
What Should I Have Ready When I Call?
Have the model number from the outdoor unit label, a photo of the code, and a note of any recent storms, heavy rain, pest activity or previous repairs. Let us know how the outdoor unit is accessed, for example at ground level, on a balcony or on a roof, so the right equipment comes on the day. If the unit is behind a locked gate, arrange access in advance so the technician can start work promptly.
Related Codes
Which LG Codes Relate to CH41?
These sibling pages explain other codes that involve outdoor sensors or compressor protection.
LG CH44
The outdoor air temperature sensor.
LG CH38
Low refrigerant protection, which relies on discharge readings.
LG CH26
Compressor start or rotation failure.
Browse every covered code on our LG air conditioner error codes hub, or visit the error code library for other brands.
Getting a Technician Out
Can You Arrange a CH41 Repair Near Me?
Yes. We book licensed technicians for LG outdoor sensor faults across Sydney, Melbourne, Brisbane, Perth and Adelaide.
See our national LG air conditioning page, or the local pages for LG Sydney, LG Brisbane, LG Perth and LG Adelaide. Rapid Air Cooling is a booking service, not affiliated with LG. The technicians we send hold the licences their work requires.
Questions
Frequently Asked Questions
Does CH41 mean my compressor is overheating?
No. CH41 means the discharge sensor reading is missing or impossible. A genuine overheating condition is usually reported with a different code.
Is CH41 an expensive repair?
Usually it is a sensor or lead replacement, which is a modest job. If the outdoor board input has failed, the repair is larger and you will be told first.
Why did CH41 appear after heavy rain?
Water reaching the sensor plug or lead can upset the reading. If it does not clear once things dry out, a technician should check for corrosion or damage.
Could animals have caused CH41?
Yes. Rodents and insects sometimes damage sensor leads inside outdoor units. Mention any signs of pests when you book.
Can I open the outdoor unit to check the sensor?
No. The inverter board holds a high voltage charge and the pipes get very hot. A licensed technician should do this with the power isolated.
Will the code come back after a sensor replacement?
Not if the cause is fixed and the sensor is refitted securely. Repeat faults often trace back to poor fitting or a lead routed near hot or sharp parts.
Where can I read about other faults?
Our troubleshooting guide covers common problems, and our page on air conditioning service Australia explains how we work.
LG Showing CH41?
Call with the code and we will arrange a licensed technician to test the discharge sensor, refit it properly and get the compressor protected again.
Reviewed by AC repair and service specialist on 22 October 2026. How we write our articles