LG Air Conditioner Error Code E215

E215 indicates an MCU branch part setup error caused by overlapping indoor unit address assignments across one or more MCUs in the system. The LG multi-zone system requires every indoor unit to have a unique address so the controller can communicate with each unit individually. When duplicate addresses are detected, the system halts normal operation and displays E215 until the conflict is resolved.

E215 is a configuration conflict that prevents the MCU from properly controlling all indoor units, so normal operation will be disrupted or inhibited while the error is active. Running the system in this state risks incorrect control signals being sent to the wrong units. The error should be resolved by a qualified technician before relying on the system for regular use.

If the fix involves only reprogramming the address switches, the cost is primarily a service call and labor fee, typically ranging from $75 to $200 depending on the technician and location. If a faulty MCU is identified as the root cause and needs replacement, parts and labor costs can range from $300 to $700 or more depending on the specific model and system size. Getting an itemized diagnostic estimate before authorizing any parts replacement is recommended.

To fix E215, locate the address setup switches (typically DIP or rotary switches) on each indoor unit's control board and map out all currently assigned addresses. Identify any duplicates and change the conflicting unit's switch to a unique, unused address value. Once all addresses are unique across every MCU branch, press the K3 button on the MCU to reset the system and clear the error.

A simple power reset will not permanently clear E215 because the underlying address conflict still exists in the hardware switch settings. The K3 button on the MCU is used to reset the controller after the address overlap has been corrected, not as a standalone fix. The duplicate address assignments must be resolved first, otherwise the error will return immediately after any reset.