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Error code reference

Fisher & Paykel Refrigerator Error Code 4

Filter sensor hot

Fisher & Paykel codesFisher & Paykel refrigerator codes

Filter sensor hot - faulty filter temperature sensor with resistance out of normal range (resistance less than 660 Ohms).

First step from the service manual

Check the resistance of the filter temperature sensor. If faulty, replace.

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

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What 4 means on a Fisher & Paykel refrigerator

Error Code 4 on a Fisher & Paykel refrigerator indicates that the filter temperature sensor has reported a resistance value below 660 Ohms, which falls outside the acceptable operating range. This condition is flagged as a "filter sensor hot" fault, meaning the control board has detected an abnormally low resistance reading from the sensor. In most NTC (negative temperature coefficient) thermistor-based sensors, resistance decreases as temperature rises, so a reading below the minimum threshold suggests the sensor is reporting an extremely high temperature, or more commonly, that the sensor itself has failed in a shorted or degraded state.

The filter temperature sensor monitors the temperature at or near the water filter assembly in the refrigerator. This data is used by the control system to ensure the filter and surrounding components are operating within safe thermal limits. When the resistance drops below 660 Ohms, the control board can no longer trust the sensor's readings and triggers Error Code 4 to alert the technician to a measurement anomaly.

The primary diagnostic step is to disconnect the sensor and measure its resistance directly with a multimeter. A reading below 660 Ohms confirms the sensor has failed and requires replacement. It is also worth inspecting the wiring harness between the sensor and the control board for any shorts to ground, pinched wires, or damaged connector pins, as these wiring faults can produce the same low-resistance reading even when the sensor itself is intact.

Source: manufacturer service documentation.

Common causes of 4

  1. 01

    Failed filter temperature sensor

    Part replacement

    The sensor itself has degraded internally, causing its resistance to drop below 660 Ohms. This is the most common cause and is confirmed by measuring resistance directly at the sensor terminals with a multimeter.

  2. 02

    Short circuit in sensor wiring

    Wiring / connection

    A wire in the harness connecting the sensor to the control board may be shorted to ground or to another conductor, artificially pulling the resistance reading below the threshold. Inspect the harness for pinched, chafed, or melted insulation.

  3. 03

    Damaged or corroded sensor connector

    Wiring / connection

    Moisture or physical damage at the connector pins can create a low-resistance path that mimics a failed sensor. Clean or replace the connector and retest before condemning the sensor.

  4. 04

    Control board fault

    Part replacement

    In rare cases, the control board's sensor input circuit can fail, causing it to misread a normal sensor as out of range. This should only be suspected after the sensor and wiring have been confirmed good.

See the test procedure for each cause

Frequently asked questions about 4

What does 4 mean on a Fisher & Paykel refrigerator?
Error Code 4 on a Fisher & Paykel refrigerator indicates a faulty filter temperature sensor. The sensor's resistance has dropped below 660 Ohms, which is outside the normal operating range. This is typically caused by a failed sensor or a short in the sensor wiring. The sensor resistance should be measured with a multimeter to confirm the fault.
How do I fix Error Code 4 on my Fisher & Paykel refrigerator?
Start by disconnecting the filter temperature sensor and measuring its resistance with a multimeter. If the reading is below 660 Ohms, the sensor has failed and needs to be replaced. Also inspect the wiring harness and connector for any signs of damage or shorting, as these can produce the same fault code even with a good sensor.
Will resetting my Fisher & Paykel refrigerator clear Error Code 4?
A reset may temporarily clear the code from the display, but if the underlying sensor fault remains, the code will return once the control board runs its diagnostic checks again. The fault needs to be physically resolved by replacing the faulty sensor or repairing the wiring before the error will stay cleared.
Is Error Code 4 on a Fisher & Paykel refrigerator a safety concern?
Error Code 4 is primarily a component reliability issue rather than an immediate safety hazard. However, a faulty temperature sensor means the refrigerator's control system is missing accurate data from that sensor location. It is best to address the fault promptly to ensure the refrigerator continues to operate as designed.
How much does it cost to fix Error Code 4 on a Fisher & Paykel refrigerator?
If only the filter temperature sensor needs replacement, parts typically cost in the range of $20 to $60, and the repair is relatively straightforward for a technician. If a professional service call is needed, total costs including labor generally fall in the range of $100 to $250 depending on your location and the service provider. Wiring repairs, if needed, may adjust the final cost.

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