LG Air Conditioner Error Code E557

E557 indicates an option code mismatch among the indoor units in a DPM (Dual Port Module) system. Each indoor unit in this type of multi-unit setup must have a compatible and consistent option code programmed into its control board. When the system detects a discrepancy between units, it triggers E557 and halts normal operation. This error is exclusive to DPM system configurations.

E557 typically prevents the DPM system from operating normally, so in most cases the units will not run while this error is active. There is no immediate safety hazard associated with this error code, as it is a configuration fault rather than an electrical or refrigerant issue. However, you should not attempt to bypass the error and should contact a technician to correct the option code settings before resuming normal operation.

If the fix involves only reprogramming the option codes on the indoor units, the cost is typically limited to a service call and labor, which can range from roughly $75 to $200 depending on the technician and location. If a faulty control board is identified as the cause and requires replacement, total costs including parts and labor can range from $200 to $600 or more depending on the specific unit model. Getting a diagnostic quote from an LG-authorized technician before approving any parts replacement is recommended.

Resolving E557 requires accessing the service-level programming menus on each indoor unit's control board, which is generally not something a homeowner can do without technical training and access to the system's configuration documentation. A qualified HVAC technician familiar with LG DPM systems should perform the option code inspection and correction. Attempting to adjust control board settings without proper knowledge can create additional configuration problems.

A simple power reset will not clear E557 because the error is caused by a persistent configuration mismatch stored in the control boards of the indoor units. The mismatch will be detected again each time the system restarts until the option codes are corrected. The underlying programming issue must be addressed before the error will go away.