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Error code reference

Miele Refrigerator Error Code F4

Freezer evaporator NTC defective (short- or open-circuited); compressor runs continuously.

Miele codesMiele refrigerator codes

Freezer evaporator NTC defective (short- or open-circuited); compressor runs continuously.

First step from the service manual

Check the NTC resistance per NTC resistance table; if defective, replace it.

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

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What F4 means on a Miele refrigerator

The F4 error code on a Miele refrigerator indicates a fault with the freezer evaporator NTC (Negative Temperature Coefficient) sensor. This sensor is a thermistor responsible for monitoring the temperature at the freezer evaporator coil and reporting that data to the control board. When the control board detects a reading outside the expected resistance range, it classifies the sensor as defective, either short-circuited (resistance too low) or open-circuited (resistance too high or no continuity). The control board loses its ability to accurately regulate the refrigeration cycle without valid temperature feedback from this sensor.

A key symptom accompanying F4 is that the compressor runs continuously. Without accurate evaporator temperature data, the control board cannot determine when the cooling cycle should stop, so it defaults to running the compressor non-stop. This can accelerate compressor wear, increase energy consumption, and may result in over-freezing or temperature imbalances throughout the unit. The evaporator fan and defrost system may also behave abnormally as a result of the missing sensor input.

Diagnosing F4 requires testing the NTC sensor's resistance with a multimeter and comparing the reading against the NTC resistance table specific to the unit. Resistance values for NTC sensors vary with temperature, so testing should account for the current temperature at the sensor location. A shorted sensor will show near-zero resistance, while an open-circuit sensor will show no continuity at all. If the sensor tests outside the specified range, replacement is the correct repair path. Wiring and connector integrity between the sensor and control board should also be inspected for damage or corrosion.

Source: manufacturer service documentation.

Common causes of F4

  1. 01

    Failed NTC sensor (open circuit)

    Part replacement

    The NTC thermistor has broken internally, resulting in no continuity. This is the most common cause and will show as infinite resistance when tested with a multimeter.

  2. 02

    Failed NTC sensor (short circuit)

    Part replacement

    The thermistor has shorted internally, causing near-zero resistance regardless of temperature. This is also a sensor failure and requires sensor replacement.

  3. 03

    Damaged wiring or connector

    Wiring / connection

    The wiring harness between the NTC sensor and the control board may be frayed, pinched, or corroded at the connector, mimicking an open or short circuit. Visually inspect the harness and test for continuity through the wiring before replacing the sensor.

  4. 04

    Corroded or loose sensor connector

    Wiring / connection

    Moisture inside the freezer compartment can cause corrosion at the sensor's electrical connector, creating intermittent or total loss of signal. Cleaning or reseating the connector may resolve the fault if the sensor itself tests within specification.

  5. 05

    Control board fault

    Part replacement

    If the NTC sensor and all associated wiring test correctly against the resistance table, the control board's sensor input circuit may have failed. This is the least common cause and is diagnosed only after ruling out the sensor and wiring.

See the test procedure for each cause

Frequently asked questions about F4

What does F4 mean on a Miele refrigerator?
F4 indicates that the freezer evaporator NTC temperature sensor has been detected as defective, either short-circuited or open-circuited. The control board can no longer receive valid temperature readings from the freezer evaporator, so it runs the compressor continuously as a default response. The sensor must be tested against the resistance table and replaced if it falls outside the specified range.
Can I fix F4 on my Miele refrigerator myself?
A knowledgeable DIYer with a multimeter can test the NTC sensor's resistance and inspect the wiring harness and connectors for damage. If the sensor tests as open or shorted, replacing it is a straightforward repair. However, if the wiring and sensor both test correctly, the fault may lie with the control board, which is a more complex and costly repair best handled by a qualified technician.
Will resetting the refrigerator clear the F4 error code?
Resetting the unit by cycling the power may temporarily clear the error display, but the code will return if the underlying NTC sensor fault is still present. The compressor will also continue running continuously until the root cause is repaired. A reset is not a fix and should only be used as part of the diagnostic process.
Is it safe to keep using my Miele refrigerator while F4 is active?
Continued use with F4 active is not recommended for extended periods. The compressor running without interruption accelerates wear and increases energy consumption. Food safety may also be at risk if temperature regulation becomes unpredictable. It is best to address the fault promptly or transfer perishables to another unit in the meantime.
How much does it cost to repair a Miele refrigerator F4 error?
If the NTC sensor itself is the cause, parts and labor costs are typically in the range of $100 to $300 depending on your location and service provider. If the wiring or connector is the issue, the cost may be lower since parts are minimal. A control board replacement, if required, can range from $300 to $600 or more, making accurate diagnosis before ordering parts important.

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