mypros+
Error code reference

LG Refrigerator Error Code Er RS1

Abnormal Refrigerator Sensor (1)

LG codesLG refrigerator codes

Abnormal Refrigerator Sensor (1) - cut or short circuit wire on the primary refrigerator temperature sensor.

First step from the service manual

Check for a loose connection in CON7 on main PCB.

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 Er RS1.

  • 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 Er RS1 means on a LG refrigerator

The Er RS1 error code on an LG refrigerator indicates an abnormal condition detected in the primary refrigerator compartment temperature sensor. This sensor is a thermistor, a resistive component whose electrical resistance changes predictably with temperature, allowing the main PCB to monitor internal compartment conditions. When the control board reads a signal outside the expected resistance range, it interprets the condition as either an open circuit (cut wire) or a short circuit, and triggers the Er RS1 fault to alert the technician.

The first diagnostic step is to inspect connector CON7 on the main PCB. A loose or corroded connection at this point can mimic the electrical signature of a broken or shorted sensor wire without any actual damage to the thermistor itself. Reseating the connector and checking for bent pins or oxidation should be completed before any component replacement is considered.

If CON7 checks out as secure and undamaged, the fault is most likely a physically damaged sensor wire or a failed thermistor. Wiring between the sensor and the PCB can develop breaks from repeated door opening cycles, pinched harness routing, or rodent damage. A failed thermistor will typically read either infinite resistance (open circuit) or near-zero resistance (short circuit) when measured with a multimeter, confirming the need for sensor replacement.

Source: manufacturer service documentation.

Common causes of Er RS1

  1. 01

    Loose connection at CON7 on main PCB

    Wiring / connection

    A loose or poorly seated connector at the CON7 port on the main control board is the first thing to check, as it can produce an open or short circuit reading without any actual sensor damage. Inspect the connector for bent pins, corrosion, or partial disconnection and reseat it firmly.

  2. 02

    Broken or cut sensor wire

    Part replacement

    The wiring harness running from the primary refrigerator thermistor to the PCB can develop an open circuit from pinching, stress from door movement, or physical damage. Visually trace the harness for visible breaks, kinks, or frayed insulation.

  3. 03

    Shorted sensor wire

    Part replacement

    A short circuit in the sensor wiring can occur where insulation has worn through and two conductors contact each other or contact a grounded surface. This produces a near-zero resistance reading at the PCB and triggers the Er RS1 fault.

  4. 04

    Failed refrigerator thermistor

    Part replacement

    The thermistor itself can fail internally, reading either infinite resistance or zero resistance regardless of temperature. Confirm by disconnecting the sensor and measuring its resistance with a multimeter at a known temperature.

  5. 05

    Damaged or faulty main PCB

    Part replacement

    In less common cases, the CON7 port or the sensor input circuit on the main control board itself may be damaged, causing false fault readings even when the sensor and wiring are intact. This is typically diagnosed only after confirming all wiring and sensor components are good.

See the test procedure for each cause

Frequently asked questions about Er RS1

What does Er RS1 mean on a LG refrigerator?
Er RS1 means the main control board has detected an abnormal signal from the primary refrigerator compartment temperature sensor. The fault indicates either a cut wire (open circuit) or a short circuit somewhere between the thermistor and the PCB. LG refrigerators use this sensor to regulate cooling in the fresh food section, so the error should be addressed promptly to avoid temperature control issues.
How do I fix the Er RS1 error on my LG refrigerator?
Start by inspecting the CON7 connector on the main PCB for a loose or corroded connection and reseat it firmly. If the error persists, trace the sensor wiring harness for visible damage such as breaks or worn insulation. If the wiring looks intact, use a multimeter to test the thermistor resistance and replace the sensor if it reads open or shorted. In rare cases, the main PCB itself may need replacement if the sensor and wiring test correctly.
Is it safe to keep using my refrigerator while Er RS1 is displayed?
Continued use is risky because the refrigerator cannot accurately monitor the internal temperature of the fresh food compartment when the primary sensor is faulted. This may cause the compressor to run improperly, resulting in either overcooling or insufficient cooling. Perishable food safety can be compromised, so the issue should be diagnosed and repaired as soon as possible.
Will resetting my LG refrigerator clear the Er RS1 error?
A power reset may temporarily clear the error display, but the code will return if the underlying wiring or sensor fault still exists. Resetting without repairing the root cause does not fix the problem and can delay a proper diagnosis. The error should be resolved through inspection and repair of the sensor circuit rather than relying on resets.
How much does it cost to repair an Er RS1 error on an LG refrigerator?
If the fix is simply reseating the CON7 connector, there is no parts cost and only minimal labor time involved. Replacing a faulty thermistor sensor is generally an inexpensive repair, with parts typically ranging from $15 to $50 and professional labor adding $75 to $150 depending on your area. If the main PCB needs replacement, total costs including parts and labor can range from $200 to $450 or more.

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