mypros+
Error code reference

LG Refrigerator Error Code R0 R1 R2 ON, R3 R4 OFF

Defrost operation failure

LG codesLG refrigerator codes

Defrost operation failure — defrost heater wires are cut or disconnected.

First step from the service manual

Check defrost heater wiring and connections.

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

MyPros+ Max

Get the full diagnostic procedure for R0 R1 R2 ON, R3 R4 OFF.

  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
Get the full procedure

$29/month · Cancel anytime · Or $9.95 3-day pass

What R0 R1 R2 ON, R3 R4 OFF means on a LG refrigerator

The error combination R0 R1 R2 ON with R3 R4 OFF on an LG refrigerator signals a defrost operation failure caused by a break in the defrost heater circuit. In LG's relay-based diagnostic display system, the R-codes represent the state of specific relays and components within the sealed system and defrost circuit. When R0, R1, and R2 are active (ON) while R3 and R4 remain off, the control board has detected that the defrost heater is not completing its circuit, which points directly to an open or disconnected wiring condition rather than a failed heater element itself.

The defrost heater is responsible for melting frost accumulation off the evaporator coils during scheduled defrost cycles. If the wiring feeding the heater is cut, corroded, or has pulled free from a connector, the heater cannot activate and frost will build up continuously on the evaporator. This leads to restricted airflow through the evaporator coils, reduced cooling performance, and eventually complete loss of refrigeration if left unaddressed.

The first diagnostic step is a thorough inspection of the defrost heater wiring harness and all associated connectors. Technicians should trace the wiring from the control board through the freezer compartment to the heater terminals, looking for visible breaks, burned insulation, corrosion at connector pins, or terminals that have backed out of their housings. A continuity test across the heater circuit will confirm whether the open condition is in the wiring or at a connection point. If wiring continuity is confirmed, the issue may be isolated to a specific connector or terminal rather than the heater element itself.

Source: manufacturer service documentation.

Common causes of R0 R1 R2 ON, R3 R4 OFF

  1. 01

    Disconnected defrost heater wiring connector

    Wiring / connection

    A connector in the defrost heater circuit may have vibrated loose, been accidentally unplugged during a previous repair, or have a terminal that has backed out of its housing. Inspecting each connector in the heater circuit and pressing them firmly together is the first physical check to perform.

  2. 02

    Broken or cut heater wire

    Part replacement

    The wiring harness running to the defrost heater can develop a break in the conductor due to repeated freezer temperature cycling, physical damage, or contact with a sharp edge inside the freezer compartment. A continuity test along the wire length will identify the break point.

  3. 03

    Corroded or burned connector terminals

    Part replacement

    Moisture inside the freezer compartment can corrode connector pins over time, creating high resistance or a complete open in the heater circuit. Burned terminals can result from a prior loose connection arcing under load. Visible discoloration or white oxidation at the connector is a reliable indicator.

  4. 04

    Wiring damaged during prior service

    Part replacement

    If the refrigerator has been serviced before, a wire in the defrost heater circuit may have been pinched, nicked, or incompletely reconnected during reassembly. Checking the service history and carefully inspecting any area that was previously accessed can help isolate this cause.

See the test procedure for each cause

Frequently asked questions about R0 R1 R2 ON, R3 R4 OFF

What does R0 R1 R2 ON, R3 R4 OFF mean on a LG refrigerator?
This error code indicates a defrost operation failure caused by cut or disconnected wiring in the defrost heater circuit. The relay status combination tells the control board that the heater circuit is open and the heater cannot operate. Without a working defrost heater, frost will accumulate on the evaporator coils and cooling performance will deteriorate. The wiring harness and all connectors in the defrost heater circuit need to be inspected.
How do I fix the R0 R1 R2 ON, R3 R4 OFF error on my LG refrigerator?
Start by unplugging the refrigerator and locating the defrost heater wiring harness inside the freezer compartment. Check every connector for a secure fit, and look for visible wire breaks, burned insulation, or corroded terminals. Use a multimeter to perform a continuity test along the circuit to pinpoint any open condition. If a broken wire or damaged connector is found, the affected section of wiring or the connector will need to be repaired or replaced.
Is it safe to keep using my LG refrigerator when this error is displayed?
Continuing to run the refrigerator with this error active is not recommended. Without a functional defrost heater, frost will build up progressively on the evaporator coils, eventually blocking airflow entirely and causing the refrigerator to stop cooling. Food safety becomes a concern as temperatures rise. Addressing the wiring fault promptly will prevent further complications.
Will resetting my LG refrigerator clear this error code?
A power reset will not resolve this error because the underlying cause is a physical wiring fault in the defrost heater circuit. The code will return as soon as the control board attempts another defrost cycle and detects the open circuit again. The wiring issue must be repaired before the error will clear permanently.
How much does it cost to fix the defrost heater wiring on an LG refrigerator?
Repair costs depend on the extent of the wiring damage and whether parts need to be replaced. If only a connector needs to be reseated or a terminal repaired, labor costs alone may range from $75 to $150. If a wiring harness section or connector assembly requires replacement, total parts and labor costs typically range from $150 to $350 depending on the model and local labor rates.

Related LG refrigerator codes

All LG refrigerator codes
View all 485 LG refrigerator codes

78,000+ service manuals · 160,000+ error codes · 55+ brands

Get Started

$29/month · Cancel anytime · Or $9.95 3-day pass