Error Code Er FS
The Er FS code means the freezer temperature sensor (thermistor) has failed. This sensor is a small bead or probe mounted on or near the evaporator that reports the freezer temperature to the main control board. A shorted or open sensor sends an incorrect reading, causing the board to run the compressor too much, too little, or not at all. You get a freezer that is either too warm or frozen solid.
Common Causes
Open thermistor circuit: The thermistor wire breaks internally or at its solder joint. The board reads infinite resistance and triggers Er FS.
Shorted thermistor: Moisture infiltration shorts the thermistor element. The board reads near-zero resistance, interprets it as an extremely high temperature, and runs the compressor nonstop.
Damaged sensor harness: The thin wires connecting the thermistor to the main board get pinched or cracked by the evaporator cover, ice buildup, or vibration.
Main control board failure: The analog-to-digital converter circuit on the board that reads the sensor signal fails. The sensor itself is fine. This is rare but happens on older units.
DIY Troubleshooting
Reset the refrigerator: Unplug the unit for 5 minutes. Plug it back in. If Er FS clears and does not return within a few hours, a temporary glitch caused the error. Monitor the freezer temperature for 24 hours.
Locate the freezer sensor: Open the freezer door. Remove the rear evaporator cover panel (Phillips screws). The freezer thermistor is typically clipped to the evaporator tubing or mounted on the evaporator housing. It is a small plastic-coated bead with two thin wires.
Test the thermistor with a multimeter: Disconnect the thermistor harness. Set your multimeter to the 20K-ohm range. At room temperature (around 77 degrees F), a typical LG freezer thermistor reads approximately 5,000 ohms (5K). At freezer temperature (around 0 degrees F), it reads roughly 16,000-17,000 ohms. OL or zero ohms means the sensor has failed. Replace it.
Inspect the sensor wiring: Trace the two sensor wires from the thermistor back to the main harness connector. Look for cuts, pinch points, or corroded splices. Repair damaged wires with butt connectors and heat-shrink tubing.
Replace the thermistor: Order the correct freezer thermistor for your LG model number (check the model tag inside the fresh food section). Unclip the old sensor from the evaporator. Clip the new one in the same location. Route the wires along the same path and connect the harness. Reinstall the evaporator cover.
Professional Repair
A thermistor replacement is a quick repair for a trained technician. If your sensor reads correctly but the code persists, the main control board needs diagnosis. TruePro's $59 diagnostic is credited toward the repair. All sensor and board replacements carry a 90-day parts and labor warranty. CA License #51112. Same-day service is often available in LA County, Orange County, and Ventura County. Call 877-378-3111. First-time customers get 15% off labor with code NEW15.
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FAQ
What does LG error code Er FS mean?
The Er FS code means the freezer temperature sensor (thermistor) has failed. This sensor is a small bead or probe mounted on or near the evaporator that reports the freezer temperature to the main control board. A shorted or open sensor sends an incorrect reading, causing the board to run the compressor too much, too little, or not at all. You get a freezer that is either too warm or frozen solid.
Can I fix error code Er FS myself?
1. Reset the refrigerator: Unplug the unit for 5 minutes. Plug it back in. If Er FS clears and does not return within a few hours, a temporary glitch caused the error. Monitor the freezer temperature for 24 hours. 2. Locate the freezer sensor: Open the freezer door. Remove the rear evaporator cover panel (Phillips screws). The freezer thermistor is typically clipped to the evaporator tubing or mounted on the evaporator housing. It is a small plastic-coated bead with two thin wires. 3. Test the thermistor with a multimeter: Disconnect the thermistor harness. Set your multimeter to the 20K-ohm range. At room temperature (around 77 degrees F), a typical LG freezer thermistor reads approximately 5,000 ohms (5K). At freezer temperature (around 0 degrees F), it reads roughly 16,000-17,000 ohms. OL or zero ohms means the sensor has failed. Replace it. 4. Inspect the sensor wiring: Trace the two sensor wires from the thermistor back to the main harness connector. Look for cuts, pinch points, or corroded splices. Repair damaged wires with butt connectors and heat-shrink tubing. 5. Replace the thermistor: Order the correct freezer thermistor for your LG model number (check the model tag inside the fresh food section). Unclip the old sensor from the evaporator. Clip the new one in the same location. Route the wires along the same path and connect the harness. Reinstall the evaporator cover.
How much does it cost to fix error Er FS?
Typical repair costs: DIY: $15 - $45 | Pro: $140 - $260. Free diagnostic with approved repair.
Estimated Cost
DIY: $15 - $45 | Pro: $140 - $260
Free diagnostic with approved repair
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