LG Refrigerator Sensor Replacement — Thermistors and Temperature Monitoring
LG refrigerators use multiple NTC thermistors to monitor temperatures at different points in the system. Each sensor serves a specific function, and failure of any one produces different symptoms and error codes. There is no single refrigerator sensor — there are typically 4-6 separate sensors, each independently replaceable.
Sensor Locations and Functions
Freezer thermistor: Monitors freezer compartment air temperature. Controls the compressor run cycle for the freezer. Er FF relates to this sensor when it reads out of range.
Refrigerator thermistor: Monitors fresh food compartment temperature. Controls the damper position. Er IF (or Er CF on some models) relates to this sensor.
Evaporator thermistor: Mounted on the evaporator coil. Monitors coil temperature for defrost cycle timing. When this sensor fails, the defrost system may not activate, leading to ice buildup.
Condenser thermistor (some models): Monitors condenser coil temperature. Used by the board to optimize compressor speed on inverter models.
Ice maker thermistor (some models): Monitors ice maker mold temperature to determine when ice is frozen and ready to harvest.
Do You Have the Right Tools?
Multimeter ($85), vacuum pump ($250), diagnostic software, and specialized hand tools. Our technician arrives with $15K+ in professional tools — your diagnostic is free.
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Error Code Mapping
| Error Code | Sensor | Meaning |
|---|---|---|
| Er IF | Refrigerator compartment thermistor | Sensor open or shorted |
| Er FF | Freezer compartment thermistor | Sensor open or shorted |
| Er CF | Condenser thermistor | Sensor out of range |
| Er CO | Communication error | Wiring between sensor and board |
Testing Thermistors
All LG refrigerator thermistors are NTC (negative temperature coefficient) — resistance decreases as temperature increases. Test with a multimeter:
| Temperature | Expected Resistance |
|---|---|
| 72F (room temp) | ~5,000 ohms |
| 32F (freezer) | ~16,000-20,000 ohms |
| 0F (deep freeze) | ~30,000-40,000 ohms |
Infinite resistance = open sensor. Zero resistance = shorted sensor. Either means replacement.
Safety First — Know the Risks
Appliances involve high voltage (120-240V), pressurized water, gas lines, and chemical refrigerants. Over 400 DIY repair injuries are reported yearly. Our techs are licensed and insured — let them handle the risk.
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Part Numbers and Pricing
| Part | LG Number | Price |
|---|---|---|
| Thermistor (most positions) | EBG61285804 | $10-$35 |
| Defrost sensor/bimetal | 6615JB2005H | $8-$25 |
| Aftermarket thermistor | Various | $5-$15 |
| Professional diagnosis + replacement | — | $90-$160 |
Sensors are among the cheapest refrigerator parts. The diagnostic time is worth more than the part.
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Replacement Procedure
Sensor locations vary by model, but all are small components with 2-wire connectors clipped or taped to their mounting surface.
Freezer/refrigerator thermistor: Usually clipped to the air duct or mounted on the inside wall. Remove the sensor cover (if present), disconnect the connector, remove the clip, install the new sensor.
Evaporator thermistor: Behind the rear freezer panel. Requires removing freezer shelves and the rear panel. The sensor clips to the evaporator coil surface.
Each swap takes 10-20 minutes once you locate the sensor.
The Real Cost of DIY
Average DIY attempt: $150-400 in tools you may use once, plus the risk of further damage. Our diagnostic visit costs $0 — we find the problem and give you an honest quote.
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Frequently Asked Questions
My LG refrigerator shows Er IF. What does that mean?
Er IF = the refrigerator compartment thermistor is reading out of range. Test its resistance — it should be approximately 5,000 ohms at room temperature. If open or shorted, replace it ($10-$35).
Can a bad sensor cause my LG refrigerator to freeze food in the fresh food section?
Yes. If the refrigerator thermistor reads warmer than actual temperature, the board runs the compressor too aggressively and overcools the compartment. Lettuce and produce freezing is a common symptom of a drifted thermistor.
How many sensors does my LG refrigerator have?
Typically 4-6 depending on features. Basic models have freezer, refrigerator, and evaporator sensors. Models with ice makers, water dispensers, and smart features have additional sensors.
LG refrigerator showing Er codes? Our technicians test all sensors and replace the failed one on-site. Book a technician →
