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Error code reference

LG Hvac Error Code E201

MASTER ERV tracking error

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MASTER ERV tracking error — after 3 minutes of tracking, SLAVE ventilators cannot be detected (tracking carried out 5 times with no response).

First step from the service manual

Press RESET KEY K3 on MASTER PCB to check number of SLAVEs responding to tracking.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What E201 means on a LG hvac

The E201 error code on an LG ERV (Energy Recovery Ventilator) system indicates a MASTER-to-SLAVE tracking failure. In a networked ERV installation, the MASTER PCB is responsible for detecting and communicating with one or more SLAVE ventilator units during an initialization process called tracking. When the MASTER unit runs this tracking routine for 3 minutes across 5 consecutive attempts and receives no valid response from any SLAVE unit, the system logs E201 and halts coordinated operation. This is a network-level communication fault, not a mechanical failure of any fan or motor.

The tracking process depends on a functioning data communication line between the MASTER PCB and each SLAVE unit's PCB. If that communication pathway is broken, shorted, or incorrectly wired, the MASTER will complete all 5 tracking cycles without acknowledgment and trigger E201. The fault can also occur if a SLAVE PCB has lost power, failed internally, or if the network addressing configuration does not match the physical wiring layout. In multi-unit installations, even a single improperly connected SLAVE can disrupt the entire tracking sequence depending on system configuration.

The first diagnostic step is to press the RESET KEY K3 on the MASTER PCB and observe how many SLAVE units respond to the re-initiated tracking sequence. This narrows the fault to a specific unit or confirms a wiring-level issue affecting all SLAVE units simultaneously. If zero SLAVEs respond after reset, focus on shared communication wiring and power supply to the SLAVE units. If one or more SLAVEs respond but others do not, isolate the non-responding units individually for PCB and wiring inspection.

Source: manufacturer service documentation.

Common causes of E201

  1. 01

    Damaged or disconnected communication wiring

    Wiring / connection

    The data communication cable between the MASTER PCB and one or more SLAVE units may be broken, unplugged, or miswired. Inspect all communication line connections at both the MASTER and SLAVE terminals for loose, corroded, or severed wires.

  2. 02

    Loss of power to SLAVE unit(s)

    Wiring / connection

    If a SLAVE ERV unit has no power supply, its PCB cannot respond to tracking signals from the MASTER. Check that each SLAVE unit is receiving proper supply voltage and that circuit breakers feeding those units are not tripped.

  3. 03

    Failed SLAVE PCB

    Part replacement

    A defective or burned-out PCB inside one or more SLAVE units will prevent any response to the MASTER tracking routine. After confirming power and wiring are intact, the SLAVE PCB itself may need to be tested and replaced.

  4. 04

    Failed or damaged MASTER PCB

    Part replacement

    If the MASTER PCB's communication output circuit is faulty, it may be transmitting tracking signals incorrectly or not at all, causing all SLAVE units to appear non-responsive even when they are functioning normally.

  5. 05

    Incorrect network configuration or addressing

    Wiring / connection

    If the SLAVE units are not configured with the correct network addresses to match the MASTER's expected setup, the MASTER will not recognize their responses during tracking. Verify that all unit addressing settings match the system's installation requirements.

See the test procedure for each cause

Frequently asked questions about E201

What does E201 mean on a LG hvac?
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.
How do I fix the E201 error on my LG ERV system?
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.
Is the E201 error on an LG ventilation system a safety hazard?
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.
Will resetting the system clear the E201 error permanently?
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.
How much does it cost to repair an LG ERV E201 error?
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.

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