LG Heat Pump Error Code 04

Error code 04 on an LG heat pump indicates a drain pump malfunction. The float switch in the drain pan is reporting a full condition even though the control board has sent an activation signal to the drain pump. This conflict causes the unit to stop operating to prevent potential water overflow. The issue lies either with the drain pump itself, the drain line, or the float switch.

No. Error code 04 indicates the unit cannot properly remove condensate water, and the system typically locks out to protect itself and your home from overflow damage. Continuing to force the unit to operate without resolving the drain issue risks water damage to internal electrical components and potential flooding in the area where the unit is installed. Address the underlying cause before returning the unit to service.

Repair costs vary depending on the cause. Clearing a clogged drain line is generally the least expensive fix, often requiring only labor. Replacing a float switch typically falls in the range of $20 to $80 for parts, plus labor. A drain pump replacement can range from $50 to $200 or more for the part depending on the model, with additional labor costs on top. A technician visit for diagnosis and repair typically adds $75 to $150 or more depending on your location.

Start by checking whether the drain pan contains standing water. If water is present, the pump may be seized or the drain line may be blocked, both of which need to be cleared before the unit will resume operation. If the pan is dry and the error persists, inspect the float switch for debris or sticking and test it for proper continuity. Replace the drain pump or float switch if either component tests as faulty.

A reset may temporarily clear the displayed error, but the code will return if the underlying problem with the drain pump, drain line, or float switch has not been corrected. Resetting without diagnosing the root cause does not address the water management failure. A proper repair or component replacement is required for the error to stay cleared.