LG Heat Pump Error Code E602

E602 indicates a communication error between the master wired remote controller and the slave wired remote controller in the LG heat pump system. The two controllers have lost their data link, which prevents them from coordinating properly. This is commonly caused by wiring faults, loose connections, or a controller configuration issue. A technician will need to inspect the communication wiring and controller settings to diagnose the root cause.

E602 is a communication fault, not a safety-critical failure like a refrigerant leak or electrical short. However, when the master and slave controllers cannot communicate, the system may not respond correctly to commands or may operate in a degraded or unpredictable state. It is best to address the error promptly to ensure the heat pump operates as intended and does not develop further issues from the loss of controller coordination.

Repair costs for E602 vary depending on the cause. If the fix involves tightening a loose connection or adjusting controller settings, labor costs alone may range from around $75 to $150. If communication wiring needs to be replaced, expect costs in the $100 to $300 range depending on the cable run length. A failed controller PCB replacement can bring the total to anywhere from $200 to $600 or more, including parts and labor. Getting a diagnostic visit from a qualified technician is the best way to get an accurate estimate.

Some causes of E602, such as a loose terminal connection or an incorrect controller configuration, may be within reach of a knowledgeable DIYer who is comfortable working with low-voltage wiring and system settings. However, diagnosing wiring faults, testing for continuity, and replacing a failed controller PCB typically require proper tools and technical familiarity with the system. If you are not confident working with these components, it is best to contact a qualified HVAC technician.

A power reset may temporarily clear the E602 error if the communication disruption was caused by a transient issue, but the code will return if the underlying fault, such as damaged wiring or a loose connection, is still present. A reset is a reasonable first step to check if the error was a one-time occurrence, but a persistent E602 requires proper diagnosis and repair to fully resolve.