HVAC Code Lookup

LG Mini-Split: 4 Flashes

A LG mini-split LED pattern starting with 4 flashes matches 9 documented codes: CH04, CH40, CH41, CH42, CH43, CH44, CH45, CH46, CH48. Watch the full pattern (short vs. long flashes) to tell them apart — all 9 are explained below.

Code CH04: Drain pump / float switch error

Soft lockoutShown as: Indoor unit LED1 (units place) blinks 4 times

Drain pump / float switch error. Condensate is backing up inside the indoor unit - the float switch has tripped or the drain pump is not clearing water. LG's consumer page describes it as water formed inside the indoor unit not being drained.

Manual wording: “Drain pump malfunction.”

Documented for: LG mini-split indoor units fitted with a drain pump or float switch (cassette, ducted, and wall-mount units with an accessory pump)

Likely causes, most common first

  1. Drain pump fault
  2. Drain hose clogging
  3. Float switch fault
  4. Missing or badly seated short key (jumper) on the indoor PCB float-switch connector, on models that do not use a float switch

What you can safely check yourself

  • Follow the condensate drain line to where it exits and check for a clog, kink, or standing water
  • Check the drain line is not pinched, crushed, or running uphill
  • Clear any obvious blockage at the outdoor end of the drain line
  • Turn the system off at the breaker for one minute and back on after clearing an obvious drain blockage

When to call a technician

If the drain line is clear and CH04 returns, the drain pump or float switch inside the unit has failed and needs a technician. Do not remove or bypass the float switch - it is what stops the unit flooding your ceiling or wall.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH04

Code CH40: Current transformer

Hard lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) does not blink

Current transformer (CT) sensor error - the current-sensing circuit on the outdoor board is open or shorted.

Manual wording: “CT Sensor Error; Thermistor is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. PCB current-sensing circuit part burned out

When to call a technician

The service manual states that because CH40 is caused by burned-out components on the outdoor PCB, the board is replaced without separate inspection. Technician only.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH40

Code CH41: Inverter compressor discharge pipe

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 1 time

Inverter compressor discharge pipe (D-pipe) sensor is disconnected or shorted out. The thermistor that watches compressor discharge temperature is not reporting.

Manual wording: “Inverter compressor discharge pipe (D-Pipe) sensor is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor or bad canning sheath on the sensor wire

What you can safely check yourself

  • Turn the system off at the breaker for three minutes and back on

When to call a technician

The discharge sensor sits on hot compressor piping inside the outdoor unit's electrical area. Technician only.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH41

Code CH42: Low pressure sensor open or short

Soft lockoutShown as: Outdoor LED1 blinks 4 times, LED2 blinks 2 times (2-LED type)

Low pressure sensor open or short. The suction-side pressure transducer is not reporting a valid signal.

Manual wording: “Low pressure Sensor open/short”

Documented for: LG single-zone room air conditioner / mini-split outdoor units fitted with pressure sensors

Likely causes, most common first

  1. Bad wiring of the pressure sensor
  2. Bad pressure sensor

What you can safely check yourself

  • Turn the system off at the breaker for three minutes and back on

When to call a technician

Pressure transducers are mounted on the refrigerant circuit. Replacement is technician work.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Source

Full page for LG code CH42

Code CH43: High pressure sensor is disconnected or shorted out

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 3 times

High pressure sensor is disconnected or shorted out. The discharge-side pressure transducer is not reporting a valid signal.

Manual wording: “High pressure sensor is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units fitted with pressure sensors

Likely causes, most common first

  1. Bad wiring of the pressure sensor
  2. Bad pressure sensor

What you can safely check yourself

  • Turn the system off at the breaker for three minutes and back on

When to call a technician

Pressure transducers are mounted on the refrigerant circuit. Replacement is technician work.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH43

Code CH44: Outdoor air

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 4 times

Outdoor air (inlet) temperature sensor is disconnected or shorted out. The outdoor unit cannot read ambient temperature, so it cannot run its defrost and capacity logic.

Manual wording: “Outdoor air sensor is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor or bad canning sheath on the sensor wire

What you can safely check yourself

  • Turn the system off at the breaker for three minutes and back on

When to call a technician

The ambient sensor is inside the outdoor unit's cabinet. Measuring and replacing it is technician work.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH44

Code CH45: Mid-pipe thermistor of the outdoor unit condenser coil is disconnected or shorted out

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 5 times

Mid-pipe thermistor of the outdoor unit condenser coil is disconnected or shorted out. This is the sensor the unit uses to judge coil temperature for defrost.

Manual wording: “Mid-pipe thermistor of outdoor unit condenser is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor or bad canning sheath on the sensor wire

What you can safely check yourself

  • Turn the system off at the breaker for three minutes and back on

When to call a technician

The coil sensor is clamped to refrigerant piping inside the outdoor cabinet. Technician only.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH45

Code CH46: Outdoor unit suction pipe thermistor is disconnected or shorted out

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 6 times

Outdoor unit suction pipe thermistor is disconnected or shorted out. The sensor on the compressor suction line is not reporting.

Manual wording: “Outdoor unit suction piping thermistor is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor or bad canning sheath on the sensor wire

What you can safely check yourself

  • Turn the system off at the breaker for three minutes and back on

When to call a technician

The suction sensor is on refrigerant piping inside the outdoor cabinet. Technician only.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH46

Code CH48: Outdoor unit condenser coil outlet

Soft lockoutShown as: Outdoor LED01 (red) blinks 4 times, LED02 (green) blinks 8 times

Outdoor unit condenser coil outlet (liquid line) thermistor is disconnected or shorted out.

Manual wording: “Outlet piping (liquid) of condenser is disconnected or has shorted out”

Documented for: All LG residential mini-split outdoor units

Likely causes, most common first

  1. Sensor mis-wiring or short at the connector
  2. Moisture penetration into the sensor or bad canning sheath on the sensor wire

What you can safely check yourself

  • Turn the system off at the breaker for three minutes and back on

When to call a technician

The liquid line sensor is on refrigerant piping inside the outdoor cabinet. Technician only.

A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Full page for LG code CH48

Other LG codes