LG Air Conditioner Error Code 5

Error code 5 on an LG air conditioner means the system has detected a loss of communication between the indoor and outdoor unit control boards. The indoor unit monitors a dedicated communication line and triggers this code when the signal is absent or too degraded to process. The fault usually points to the communication wire, its terminals, or one of the two control boards.

No. When error code 5 is active, the indoor and outdoor units cannot coordinate with each other, so the system will not run a normal cooling or heating cycle. Attempting to force operation is not possible through normal controls while the fault is present. The error must be cleared by resolving the underlying communication fault before the system will operate.

A power reset by turning off the breaker for 60 seconds may temporarily clear error code 5, but it will return if the communication fault has not been repaired. A reset is a useful first step to rule out a transient signal glitch, but persistent reappearance of the code means there is a wiring, connection, or board fault that requires physical inspection and repair.

Start by powering the system off at the breaker for 60 seconds, then restart. If error code 5 returns, inspect the communication wire and its terminals at both the indoor and outdoor units for loose connections, corrosion, or physical damage. Tighten any loose terminals and clean corroded connections. If the wiring checks out, a technician will need to test voltage and signal on the communication circuit to determine whether the indoor or outdoor control board has failed.

If the fix involves tightening a loose terminal or replacing a damaged communication wire, labor costs are typically in the range of $75 to $150 depending on your area. If one of the control boards has failed, parts cost between $150 and $400 for an LG PCB depending on the model, plus labor. Getting a technician to diagnose which component has failed before ordering parts will save money and avoid unnecessary replacements.