LG · Refrigerator
LG Refrigerator FS Error Code
Freezer sensor reading invalid
What this error means
FS reports a Freezer Sensor error—the thermistor in the freezer compartment sent resistance outside the expected range, so the board cannot regulate defrost and compressor run time accurately.
How FS is detected
When FS appears on a LG refrigerator, the control board has confirmed that water did not leave the machine within the programmed drain window. On LG LFXS26596S, LG LRFXS2503S, and similar variants, the drain pump runs for a fixed interval—often three to seven minutes on washers and dishwashers—while a pressure switch or turbidity sensor verifies the tub or sump is empty. If water remains, the cycle stops to prevent spin with a full tub or overflow on the next fill.
Most FS calls are resolved without parts: power off and reseat the freezer sensor plug at the main board. Restricted drain paths mimic pump failure because the impeller spins against a blocked hose or filter. Document whether the pump hums audibly during the drain step; a humming pump with no water movement points to a clogged filter or kinked hose, while silence may indicate a failed pump motor or loose wiring at the harness.
After clearing blockages, run a short cycle and listen at the drain hose for steady water flow. If FS returns on the next load with a clean filter and straight hose, measure resistance at the pump motor connector per the service manual for your model before ordering a replacement pump assembly.
Common causes
- Thermistor wire broken at the evaporator clip
- Connector corrosion after defrost water exposure
- Shorted sensor from ice piercing the harness
- Control board input circuit failure
Step-by-step fixes
- 1Power off and reseat the freezer sensor plug at the main board
- 2Inspect wires along the freezer liner for pinches
- 3If freezer temp on display reads --- or jumps wildly, sensor is suspect
- 4Allow a full hour after reseat before judging FS clearance
When to call a technician
Technicians ohm the freezer thermistor at 77°F against LG spec—typically ~5kΩ depending on model.
Affected models
- LG LFXS26596S
- LG LRFXS2503S
- LG LFXC22526S
Prevention & maintenance
- Clean drain filters and hose terminations monthly on high-use refrigerators to prevent FS from lint and food debris buildup.
- Record when FS appears in the cycle and whether it clears after a 60-second power reset on your LG refrigerator—that detail speeds diagnosis if you call service.
- Keep the model and serial number from the rating plate when ordering parts for FS; LG uses multiple revisions with different harness lengths and board firmware.
- Photograph wiring connector orientation before disconnecting any component while troubleshooting FS; reversed plugs on pumps and valves cause immediate repeat faults.