LG Refrigerator Error Code RT sensor failure

The RT sensor failure code on an LG refrigerator indicates that the room temperature (RT) sensor has experienced either an open circuit (cut wire) or a short circuit condition. The RT sensor monitors the ambient temperature surrounding the refrigerator, and this data is used by the control board to make operational adjustments based on the environment the unit is operating in. When the control board detects that the sensor signal is outside the expected range due to a wiring fault, it triggers this error. Visually, the failure presents in a specific way: all display LEDs will illuminate, but both the Freezer and Refrigerator temperature displays will go dark.

The diagnostic process for this error requires accessing the error display mode by pressing and holding the Freezer temp control button and the Super Freezing button simultaneously for at least one second. This forces the unit to surface the stored fault code. Once confirmed, the first physical inspection step is to examine the connecting wires on the RT sensor itself, looking for visible breaks, pinched sections, frayed insulation, or signs of a short such as melted or discolored wire insulation. Connector terminals should also be checked for corrosion or loose seating.

If the wiring appears intact, the sensor itself may have failed internally, producing a resistance reading that falls outside the acceptable range for the control board. A multimeter can be used to test sensor resistance at the connector. If the resistance is infinite (open) or near zero (short), the sensor requires replacement. Wiring harness damage between the sensor and the control board is another possible source of the fault and should be traced fully before condemning the sensor.