LG Air Conditioner Error Code E4

The E4 code means the unit detected a pipe temperature below 2 degrees Celsius after running for more than 10 minutes. This is a freeze protection fault designed to stop the system before ice can form on the evaporator coil or damage occurs to the compressor. The most likely cause is a refrigerant leak, though high ambient room temperatures and airflow restrictions can also trigger it.

No, you should not attempt to bypass or repeatedly reset the unit to keep it running while the E4 fault is active. Continued operation with a refrigerant leak or a freezing coil can cause ice to block airflow entirely and can lead to liquid refrigerant returning to the compressor, which causes serious internal damage. Allow the unit to thaw completely and address the root cause before restarting.

A power reset may temporarily clear the E4 code and allow the unit to restart, but if the underlying problem is still present, the fault will return once the unit has run for 10 minutes and the pipe temperature drops below 2 degrees again. Resetting without fixing the root cause is not a solution and can lead to more serious damage over time.

Some causes, like a clogged air filter or a room temperature that is too high, can be addressed without professional help. However, if the fault is caused by a refrigerant leak, handling refrigerant requires certification and specialized equipment, so that repair must be performed by a licensed HVAC technician. Start by cleaning the filter and checking room conditions before calling for service.

Repair costs vary widely depending on the root cause. Cleaning a dirty filter costs nothing, while a refrigerant leak repair involving leak detection, component repair, and recharge can range from $200 to $600 or more depending on the leak location and refrigerant type. A failed pipe temperature sensor replacement typically falls in the $75 to $200 range including labor.