Common error codes for LG window air conditioners include E1, E2, E3 and E4. The E4 error code is only applicable for portable LG window air conditioner units and indicates that the unit is going into defrost mode.
The E4 error code is normal if the unit is cooling down properly. However, if the E4 code appears repeatedly, then the unit's air filter should be changed.
The E1 error code indicates that the temperature sensor of the air conditioner has failed and needs to be replaced, while the E2 error refers to a failure in the indoor temperature sensor. The E3 code can indicate a failure in the indoor temperature sensor, electronic control board or damage to the unit's fan blade.