LG Refrigerator Error Code Er 1

The Er 1 error code on an LG refrigerator indicates a failure in the refrigerator compartment temperature sensor. This sensor is located inside the control box and is responsible for sending real-time temperature data to the main control board. When the board detects a signal that falls outside the expected range, it registers the fault as either a short circuit or an open circuit condition in the sensor wiring or the sensor itself. Without accurate temperature readings, the refrigerator cannot properly regulate its cooling cycles.

The diagnostic process begins at CON4, which is the connector associated with the refrigerator sensor circuit. A loose or corroded connection at CON4 is the first thing to inspect, as vibration and thermal cycling over time can cause connectors to work loose. If the connection appears intact, the next step is to measure the resistance between the two White wires at CON4. A short circuit will typically show near-zero resistance, while an open circuit will show infinite or out-of-range resistance. Either reading points to a fault in the wiring harness or the sensor element itself.

Common failure points include the sensor itself developing an internal fault, the wiring harness between the sensor and the control box suffering damage such as chafing or a pinched wire, and corrosion building up at the CON4 connector pins. Identifying which component is at fault requires systematic resistance measurement and visual inspection of the wiring path from the sensor to the connector.