LG Air Conditioner Error Code E499

E499 indicates a heat sink temperature sensor error on the outdoor Fan1 PCB. The control system has detected that the thermistor monitoring the fan board's heat sink is producing a signal outside the expected range. This causes the unit to shut down to protect the board's power components from potential heat damage.

A power reset may temporarily clear the fault and allow the unit to restart, but if the underlying problem with the sensor, wiring, or PCB is still present, the E499 code will return. Resetting without diagnosing and repairing the root cause does not resolve the issue and may lead to repeated shutdowns.

Repair costs vary depending on the root cause. If the issue is a loose connector or minor wiring repair, the cost may be limited to a service call fee, typically in the range of $75 to $150. Replacing the heat sink thermistor is generally a lower-cost parts repair. Replacing the outdoor Fan1 PCB is more expensive, with parts and labor potentially ranging from $200 to $500 or more depending on the model and your location.

Some basic checks are within reach of a knowledgeable DIYer, such as clearing debris from around the outdoor unit, checking for obvious wiring damage, and reseating loose connectors. However, testing thermistor resistance, diagnosing PCB faults, and replacing board components typically require a qualified technician with the proper tools and access to live voltage circuits.

It is not recommended to continue operating the unit with an active E499 error. The fault indicates the system cannot reliably monitor the heat sink temperature on the outdoor fan board, which means thermal protection for that board is compromised. Running the unit in this condition risks damaging the PCB or its power components, potentially turning a sensor repair into a more expensive board replacement.