LG Heat Pump Error Code E344

E344 indicates a SUMP TEMP FIXED 3 sensor fault in the outdoor unit, classified as either an open or short circuit condition. The error triggers when the outdoor temperature is above -10°C and the sensor signal voltage rises above 4.95V or drops below 0.5V. These voltage thresholds correspond to temperature readings below -30°C or above 151°C, both of which are outside any realistic operating range and signal a sensor or wiring failure.

Operating the heat pump while E344 is active is not recommended. The system relies on the sump temperature sensor to manage refrigerant and compressor operation safely. Running the unit without a valid sensor reading can lead to improper operation and potential compressor or refrigerant circuit damage. The unit should remain off until the sensor fault is diagnosed and corrected.

A power reset may temporarily clear the error code from the display, but if the underlying sensor fault, such as a failed thermistor, damaged wiring, or corroded connector, is still present, the E344 code will return once the system restarts and runs diagnostics. A reset alone does not repair the fault. The sensor circuit must be inspected and the defective component repaired or replaced to permanently resolve the error.

Some basic checks such as inspecting the sensor connector for corrosion, loose pins, or a disconnected plug can be performed by a knowledgeable homeowner with the system powered down safely. However, measuring thermistor resistance and tracing wiring faults inside the outdoor unit typically requires electrical knowledge and appropriate tools. Replacing the control board, if needed, should be performed by a qualified technician to avoid further damage.

Repair costs vary depending on the root cause. Connector cleaning or a replacement thermistor sensor typically falls in the range of $75 to $250 including labor. If the outdoor main control board requires replacement, costs can range from $400 to $900 or more depending on the model and local labor rates. Getting a diagnosis from a qualified technician before ordering parts is advisable.