LG Heat Pump Error Code Dx

The Dx code indicates an OPEN or SHORT error in the EVAP IN (evaporator inlet) temperature sensor of the indoor unit whose address matches the number shown in place of "x". The sensor is responsible for measuring refrigerant temperature at the inlet of the evaporator coil. The system displays this code when the sensor's resistance signal falls outside the acceptable range, pointing to a disconnected connector, broken wiring, or a failed sensor.

The system will generally disable or limit operation of the affected indoor unit when this fault is active, which is a protective response. Running the system in this state means that indoor unit cannot properly regulate refrigerant flow, which could stress system components over time. It is best to address the fault promptly rather than continuing to operate with the code present.

A power reset may temporarily clear the code and allow the unit to restart, but if the underlying sensor fault is still present, the Dx error will return once the PCB performs its startup self-check. Resetting without repairing the root cause does not fix the problem. The code will continue to reappear until the connector, wiring, or sensor is properly inspected and corrected.

A knowledgeable DIYer can check whether the sensor connector is simply loose or disconnected at the PCB and reseat it, which may clear the code. However, measuring sensor resistance and comparing it to a specification table, tracing wiring for damage, or replacing a faulty thermistor or PCB typically requires technical experience and a multimeter. If the sensor or board needs replacement, a qualified HVAC technician is recommended.

If the fix is simply reseating a loose connector, there may be no parts cost, with labor being the primary expense. Replacing a faulty EVAP IN thermistor sensor typically costs between $20 and $80 for the part, plus labor. If the indoor unit PCB is at fault, board replacement costs can range from $150 to $400 or more for parts, plus additional labor charges.