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Error code reference

Sirius Refrigerator Error Code FF

Fresh food thermistor failure (open or short circuit detected at startup or during operation).

Sirius codesSirius refrigerator codes

Fresh food thermistor failure (open or short circuit detected at startup or during operation).

First step from the service manual

Check thermistor resistance at connector J1 pin 1 against the thermistor value table for the current temperature. All LEDs will blink every 0.5 seconds for 5 seconds on startup.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What FF means on a Sirius refrigerator

The FF error code on a Sirius refrigerator indicates a fresh food thermistor failure. The control board has detected either an open circuit or a short circuit in the thermistor circuit, meaning the sensor is either reading out of its expected resistance range or has lost continuity entirely. This failure can be detected at startup or at any point during normal operation. The thermistor is a temperature-sensitive resistor located in the fresh food compartment, and it feeds real-time temperature data to the control board so the system can regulate cooling cycles accurately.

When the FF code triggers, all LEDs on the refrigerator's display will blink every 0.5 seconds for a duration of 5 seconds during the startup sequence. This blinking pattern is the control board's built-in self-diagnostic alert, indicating it cannot establish a valid reading from the fresh food thermistor. Without reliable temperature input from this sensor, the refrigerator cannot properly manage the compressor and evaporator fan cycles for the fresh food section, which can lead to temperature instability or continuous running.

The first diagnostic step is to check the thermistor's resistance at connector J1, pin 1, and compare that reading against the thermistor resistance-versus-temperature table for the current ambient or compartment temperature. A thermistor with an open circuit will typically show infinite or very high resistance, while a shorted thermistor will show near-zero resistance. Either condition falls outside the expected value range and confirms the fault. The connector itself, wiring harness, and the thermistor body should all be inspected as part of this check.

Source: manufacturer service documentation.

Common causes of FF

  1. 01

    Failed fresh food thermistor

    Part replacement

    The thermistor itself has developed an open or short circuit internally, causing it to read outside the valid resistance range for any temperature. This is the most common root cause and is confirmed by measuring resistance at J1 pin 1 and comparing it to the temperature-resistance table.

  2. 02

    Loose or corroded connector at J1

    Wiring / connection

    The thermistor connects to the control board through connector J1, and a loose, corroded, or partially unseated connection at pin 1 can interrupt the signal and trigger the FF code. Inspect the connector for corrosion, bent pins, or incomplete seating before replacing the thermistor.

  3. 03

    Damaged wiring harness

    Part replacement

    The wiring between the thermistor and connector J1 can develop breaks, pinches, or chafing, especially near mounting clips or door hinges. A broken wire will produce the same open-circuit reading as a failed thermistor.

  4. 04

    Moisture intrusion at the sensor or connector

    Wiring / connection

    Water or ice buildup around the thermistor or at the connector can cause intermittent short circuits or corrosion that disrupts the resistance signal. This is more likely if the defrost system has not been functioning correctly.

  5. 05

    Faulty control board

    Part replacement

    If the thermistor, wiring, and connector all measure correctly against the resistance table, the control board's input circuit for the fresh food thermistor may be damaged. This is the least common cause and should only be considered after all other causes are ruled out.

See the test procedure for each cause

Frequently asked questions about FF

What does FF mean on a Sirius refrigerator?
The FF code stands for fresh food thermistor failure. It means the control board detected an open or short circuit in the temperature sensor located in the fresh food compartment, either during startup or while the refrigerator was running. When this code appears at startup, all LEDs will blink every 0.5 seconds for 5 seconds as part of the diagnostic alert. The refrigerator may not cool the fresh food section properly until the fault is resolved.
How do I fix the FF error code on my Sirius refrigerator?
Start by checking the thermistor's resistance at connector J1, pin 1, and comparing the reading to the thermistor resistance-temperature table at your current compartment temperature. If the resistance is infinite or near zero, the thermistor needs to be replaced. If the thermistor measures correctly, inspect the wiring harness and connector J1 for damage, corrosion, or loose pins before considering control board replacement.
Is it safe to keep using my refrigerator while the FF code is active?
Operating with an active FF code is not recommended for extended periods. Without a functioning fresh food thermistor, the control board cannot accurately regulate cooling in the fresh food section, which means food temperatures may rise to unsafe levels. You should address the fault promptly and monitor fresh food compartment temperatures if the refrigerator must remain in use temporarily.
Will resetting my Sirius refrigerator clear the FF code?
A power reset may temporarily clear the code, but if the thermistor or its wiring is genuinely failed, the FF code will return on the next startup or shortly after, triggering the LED blinking sequence again. The underlying electrical fault in the thermistor circuit must be repaired for the code to stay cleared.
How much does it cost to repair a Sirius refrigerator FF error code?
Repair costs vary depending on the root cause. A replacement thermistor is generally an inexpensive part, typically in the range of $15 to $50, while professional labor for diagnosis and installation can add $75 to $150 or more. If the control board is at fault, costs increase significantly, often ranging from $150 to $400 or higher depending on the board and labor rates in your area.

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