LG heat pump water heater
LG Inverter heat pump APHWC501M / 801M (2024–2025 manuals) error codes
Covers: LG Inverter Heat Pump Water Heater APHWC501M / APHWC801M / APHWC501D / APHWC801D / APHWC501L / APHWC801L - Owner's & Installation Manual MFL71409214 Rev.01 (05/08/24) and MFL71409217 Rev.00 (05/29/25) code set
Every code listed in LG's own manual for this series, with what it means and what LG says to do. Last checked 2026-10-03.
Is this your model? LG's product listings link this manual (MFL71409217, and MFL71409214 for APHWC501M) for APHWC501M, APHWC801M, APHWC501D, APHWC801D, APHWC501L and APHWC801L.
| Code | Label | What the manual says it means |
|---|---|---|
| 1 | Ambient Temp sensor is not working. | |
| 4 | Condensate drain is blocked. | |
| 6 | Lower tank Temp sensor is not working. | |
| 8 | Water detection sensor has detected leak. | |
| 9 | EEPROM error. | |
| 12 | Mid pipe Temp sensor is not working. | |
| 19 | Upper element is not working. | |
| 20 | Lower element is not working. | |
| 21 | Inverter Compressor IPM Fault | |
| 22 | Inverter input Over-Current. | |
| 23 | DC Link Low/High Volt. | |
| 26 | Compressor start failure. | |
| 29 | Compressor Over-Current. | |
| 32 | Discharge pipe is overheated. | |
| 41 | Discharge pipe Temp sensor is not working. | |
| 46 | Suction Pipe Temp sensor is not working. | |
| 52 | PCB Communication error | |
| 60 | EEPROM Check sum error(Inv.) | |
| 61 | Cond. Pipe Temp is High. | |
| 62 | Heat sink temp. is high | |
| 65 | Heat sink Temp senor [sic] is not working. | |
| 67 | BLDC motor fan is locked. | |
| DF | Not enough water in tank. | |
| EC | ECO is tripped. | |
| H1 | Water Temp is too High. | |
| H2 | Water Temp is too High. | |
| L1 | Water Temp is too Low. | |
| L2 | Water Temp is too low or upper tank Temp sensor is not working. |
LG's manual for this series does not list error codes; see the troubleshooting section below.
Safety first
- WARNING: Turn off the power by opening the circuit breaker or removing the fuses before you perform any maintenance; otherwise it may cause electrical shock resulting in severe injury or death. (pg. 28)
- DANGER: Before manually operating the relief valve, make sure it will discharge in a safe place. If water does not flow freely from the end of the discharge pipe, turn off the power to the water heater and call a qualified person. (pg. 30)
- CAUTION (Troubleshooting): For your safety, do not attempt to repair electrical wiring, controls, heating elements or other safety devices. Refer repairs to qualified service personnel. (pg. 32)
- CAUTION (ECO): You must have a qualified person investigate the cause of the high temperature condition and take corrective action before placing the water heater in service again. To reset the ECO: turn off the power, remove the front decor and upper element cover, press the red ECO RESET button. (pg. 21)
- CAUTION: Hydrogen gas can be produced in a hot water system when it is not used for a long period (generally two weeks or more). HYDROGEN GAS IS EXTREMELY FLAMMABLE. (pg. 24)
- DANGER: Higher water temperature increases the potential for hot water scalds. (pg. 24)
- Water detection model: when a water leak is detected, the (field-supplied) automatic shut-off valve shuts off the main water supply; under certain conditions water may continue to leak from the tank, however, no additional water will be added. (pg. 19)
From the manufacturer's manual for this series.
Troubleshooting without a code
Insufficient or no hot water
Likely cause: Water usage exceeds the capacity of the water heater in current mode
What to do: Wait for the water heater to recover after an abnormal demand. Change the mode for higher recovery.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 32
Insufficient or no hot water
Likely cause: Water temperature set too low
What to do: See the "Water Temperature Adjustment" section.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 32
Insufficient or no hot water
Likely cause: ECO tripped
What to do: See "Safety Controls" section.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 32
Insufficient or no hot water
Likely cause: No electric supply to the water heater
What to do: Check the electric supply to the water heater. See "Making Electrical Connections" section.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 32
Insufficient or no hot water
Likely cause: Water connections to unit are reversed
What to do: Re-install water connection correctly
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 32
Insufficient or no hot water
Likely cause: Leak in hot water faucets or plumbing system
What to do: Make certain all faucets are closed. Check home for any leaks and repair
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 32
Insufficient or no hot water
Likely cause: Improper electric wiring
What to do: See "Making Electrical Connections" section.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 32
Insufficient or no hot water
Likely cause: Cold water inlet temperature may be lower in winter
What to do: This is normal. The colder inlet water takes longer to heat.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 32
Insufficient or no hot water
Likely cause: Dirty air filter
What to do: See "Air Filter Maintenance" section.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 32
Insufficient or no hot water
Likely cause: Not enough clearance to air exchange for heat pump
What to do: Make sure unit has enough clearance. See "Select the best Location" section.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 32
Insufficient or no hot water
Likely cause: Open fuse or a circuit breaker (ELCB) tripped
What to do: Replace fuse or reset circuit breaker (ELCB).
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 33
Water is too hot
Likely cause: Water temperature set too high
What to do: See the "Water Temperature Adjustment" section.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 33
Noise
Likely cause: The heat pump compressor, fan, or EEV valve is running
What to do: This is normal
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 33
Noise
Likely cause: Build up of scale or lime deposits on heating elements may cause rumbling noise
What to do: Clean or replace the heating elements. This should only be performed by qualified service person. Call our Technical Support Center.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 33
Drips from the outside of the heater
Likely cause: Condensate drain is blocked
What to do: Clean the drain port and remove the debris.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 33
Drips from the outside of the heater
Likely cause: Hot/Cold water connections or other parts have loosened
What to do: Tighten the loose connections. This should only be done by a qualified service person.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 33
Noise and drips from relief valve
Likely cause: Pressure build-up due to thermal expansion in a closed water system.
What to do: This is an unacceptable condition and must be corrected. Do not plug the T&P relief valve outlet. Contact a plumbing contractor to correct this.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 33
Water odor
Likely cause: Certain water supplies with high sulfate content will react with the anode rod
What to do: Replacing the anode rod with less-active material rod (ex) zinc anode rod) may help reduce or eliminate the odor.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 33
Water pressure is low
Likely cause: Supply valve is partially closed
What to do: Open the water heater's supply valve fully.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 33
Trouble connecting appliance and smartphone to Wi-Fi network.
Likely cause: The password for the Wi-Fi network was entered incorrectly.
What to do: Delete your home Wi-Fi network and begin the registration process again.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 34
Trouble connecting appliance and smartphone to Wi-Fi network.
Likely cause: Mobile data for your smartphone is turned on.
What to do: Turn off the Mobile data on your smartphone before registering the appliance.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 34
Trouble connecting appliance and smartphone to Wi-Fi network.
Likely cause: The wireless network name (SSID) is set incorrectly.
What to do: The wireless network name (SSID) should be a combination of English letters and numbers. (Do not use special characters.)
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 34
Trouble connecting appliance and smartphone to Wi-Fi network.
Likely cause: The router frequency is not 2.4 GHz.
What to do: Only a 2.4 GHz router frequency is supported. Set the wireless router to 2.4 GHz and connect the appliance to the wireless router.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 34
Trouble connecting appliance and smartphone to Wi-Fi network.
Likely cause: The distance between the appliance and the router is too far.
What to do: If the router is too far from the appliance, the signal may be weak; move the router closer to the appliance or install a Wi-Fi repeater.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 34
Owner maintenance
drain and flush tank
Turn off the power by opening the circuit breaker or removing the fuses. Connect a garden hose to the drain valve and place the end of the hose in a suitable drain. Turn off the cold water supply valve. Open the drain valve (open a hot water faucet or lift the handle on the T&P relief valve to help the water drain faster). Once the tank is empty, flush the tank by opening the cold water supply valve. Allow the water to run until no more sediment drains from the tank and water runs clear. Close the drain valve and open the hot water faucet. Fill the tank by opening the cold water valve.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 28
inspect / replace anode rod
How often: after the first six months of operation, then annually or more frequently thereafter
Turn off the power. Partially drain a few quarts of water through the drain valve. Pull the front decor first, then remove the top cover; lift the front panel out. Using a box wrench, unscrew the anode rod and lift it out to inspect. Replace anode rod when more than 6" of core wire is exposed at either end of the rod. To install, seal the threads with approved sealant, thread into the port and tighten using a box wrench. Fill the tank by opening the cold water valve. Artificially softened water will make the anode rod deplete faster than normal. Do not remove anode rod from the tank except for inspection.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 29
T&P relief valve
How often: at least annually
Lift and release the lever handle on the water heater to ensure the waterways are clear and the valve operates freely.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 30
clean air filter
How often: when the "Air filter check" alarm appears on the display
Turn off the power. Hold the knobs of the air filter, pull it and remove it from the top cover. Clean the filter with a vacuum cleaner or with lukewarm water with neutral detergent. Dry the filter in the shade. Insert the air filter into the top cover and check the top cover for correct assembly of the air filter. (The air filter can be broken when it is bent.)
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 30
reset air filter alarm
The device will display an alarm icon reminding you to check and clean the air filter periodically. Press and hold Set button about 3 seconds to reset the alarm.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 24
condensate drain
Remove the condensate drain lines and connections. Pull the front decor first, then remove the top cover; lift the front panel out, then slightly lift the rear panel and remove it. Check the condensate drain pan for any debris, and clean the condensate drain by wiping out with a damp cloth or pouring a cup of bleach. Reattach top cover and side panel and connect the condensate drain line. Restore power to the water heater.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 31
extended shutdown
Turn off the power and water supply and drain the water heater to conserve energy and prevent a buildup of dangerous hydrogen gas. Drain heater and piping if they might be subjected to freezing temperatures. After a long shutdown, operation and controls should be checked by qualified service personnel; make certain the heater is completely filled again before placing it in operation.
Source: LG Heat Pump Water Heater Owner's & Installation Manual, MFL71409217 Rev.00, page 31
Sources
- LG Heat Pump Water Heater Owner's & Installation Manual (MFL71409217 Rev.00)
- LG Heat Pump Water Heater Owner's & Installation Manual (MFL71409214 Rev.01)