LG HVAC Error Code E201

E201 on an LG ERV system means the MASTER control board ran a tracking routine to detect connected SLAVE ventilator units and received no response after 5 attempts over 3 minutes. This is a network communication failure between the MASTER PCB and the SLAVE units. It can be caused by wiring faults, power loss to SLAVE units, or a failed PCB in one of the units. The system cannot coordinate ventilation across units until the communication link is restored.

The E201 error itself does not indicate a fire or refrigerant hazard, but it does mean the ventilation system is not operating as a coordinated network, which can reduce indoor air quality and energy recovery performance. If the system is not moving air properly through all zones, this could be a concern for buildings with strict ventilation requirements. It is best to have the system diagnosed and repaired promptly to restore normal operation.

Repair costs depend on the root cause. If the fault is a loose or damaged communication wire, a service visit to diagnose and repair the wiring may range from around $100 to $300 depending on labor rates and the complexity of the installation. If a SLAVE or MASTER PCB requires replacement, parts and labor combined can range from $300 to $800 or more depending on the specific board and unit model. Getting a diagnostic visit from an HVAC technician familiar with LG ERV systems is the best first step.

Start by pressing the RESET KEY K3 on the MASTER PCB to re-run the tracking sequence and observe how many SLAVE units respond. If none respond, check the communication wiring between all units and verify that each SLAVE unit has power. If some units respond and others do not, focus your inspection on the non-responding SLAVE units, checking their wiring connections and PCB condition. Persistent faults after wiring checks typically require PCB replacement by a qualified technician.

Pressing the RESET KEY K3 on the MASTER PCB re-initiates the tracking process, but it will not permanently clear the error if the underlying communication fault still exists. If the root cause such as a wiring break, power loss, or faulty PCB is not corrected, the E201 error will return after the tracking sequence completes without detecting the SLAVE units. The reset is a diagnostic tool, not a permanent fix.