LG Heat Pump Error Code E4

The E4 code on an LG heat pump signals a setting mismatch between the wired remote controller address and the indoor unit's RMC address, as defined by the SW03 dipswitch configuration on the indoor unit. This is a communication configuration error, not a refrigerant or mechanical fault. The system cannot operate normally until both addresses are set to the same value. Resetting both to address '1' is the recommended starting point for resolving the error.

The E4 error is a configuration fault, not a safety-critical failure. It prevents the heat pump from operating, but it does not indicate a dangerous condition such as a refrigerant leak or electrical hazard. However, if you are unsure about working with internal dipswitches or controller settings, it is advisable to have a qualified HVAC technician handle the adjustment to avoid introducing additional configuration errors.

If the fix only requires adjusting the SW03 dipswitches and reprogramming the wired remote controller address, labor costs for a qualified technician typically range from around $75 to $150 for a service call, depending on your region and the technician's rates. No parts are usually needed for a straightforward address mismatch. If the dipswitch assembly is damaged and requires replacement, parts and labor combined could range from $150 to $350 or more depending on parts availability.

To fix E4, locate the SW03 dipswitch bank on the indoor unit and check its current address setting. Then access the wired remote controller's address configuration and verify it matches. If you are unsure of the correct values, set both the indoor unit RMC address and the wired remote controller address to '1', which is the factory default. Once both addresses match, the error should clear and the system should resume normal operation.

A simple power cycle reset will not permanently clear the E4 error because the underlying address mismatch between the wired remote controller and the indoor unit will still exist when power is restored. The error will return until the SW03 settings and the remote controller address are corrected to match each other. Resetting both addresses to '1' and then powering the system back on is the proper resolution.