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Refrigerator Temperature sensor (thermistor): What It Does and Signs It's Failing

Small capsule-shaped sensors on a pair of wires, tucked behind a panel or clipped to the evaporator coil. Electronic fridges use several: one for each compartment, one on each evaporator to end defrost, and often one on the ice maker.

How it works

Resistance changes with temperature, and the board turns that into a reading. If a sensor reads open or shorted, the board can't trust it and sets a code.

Signs it is failing

• A sensor code for a specific compartment, defrost or ice maker
• Food freezing in the fresh food section, or a warm compartment
• Frost buildup from a defrost that never ends correctly
• Temperatures that swing for no clear reason

Sensor codes for the fridge, freezer, defrost and ice maker point here first. The wires and connectors fail too, which is why many codes mention the harness.

Can you replace it yourself?

Pull the plug before you take any panel off. Many compartment sensors sit behind a cover or the back panel and unplug from a connector. Defrost sensors are clipped to the evaporator and need the freezer back panel off. Resistance checks are a tech's job unless you know how to do one on an unplugged sensor with the manufacturer's chart.

Buying the right part

Sensors look alike but use different resistance values from brand to brand. Order the OEM part for the exact location by full model number.

Error codes linked to the temperature sensor (thermistor)

• OP / SHTemperature sensor open or shortedFrigidaire
• CCTemperature is out of rangeGE
• Er dHDefrost cycle failedLG
• Er ISIce maker sensor faultLG
• Er FSTemperature sensor faultLG
• 8EIce maker sensor errorSamsung
• 5EFridge defrost sensor errorSamsung
• 1EFreezer temperature sensor faultSamsung
• F3E1Refrigerator compartment temperature sensor faultWhirlpool
• F3E2Freezer temperature sensor faultWhirlpool
• F3E4Freezer evaporator (defrost) sensor faultWhirlpool
• F3E8 / F3E9Room temperature or humidity sensor faultWhirlpool
• F4E1Freezer defrost heater problemWhirlpool

Last reviewed 2026-10-19.