mypros+
Error code reference

Miele Washer Error Code F4257

EFU fault power failure; input voltage to EFU 235 is missing.

Miele codesMiele washer codes

EFU fault power failure; input voltage to EFU 235 is missing.

MyPros+ Max

Get the full diagnostic procedure for F4257.

  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
Get the full procedure

$29/month · Cancel anytime · Or $9.95 3-day pass

What F4257 means on a Miele washer

Error code F4257 on a Miele washer indicates a fault with the EFU (Einzel-Filter-Unit, or individual filter unit) module, specifically that the input voltage to EFU 235 is missing. The EFU is an electronic control or filtering component that requires a specific supply voltage to operate. When the machine's control system detects that this voltage is absent, it halts operation and logs the F4257 fault to prevent further damage to downstream electronics or mechanical components.

This fault is categorized as a power failure at the EFU 235 module level, meaning the issue originates in the voltage supply path leading to that component rather than within the EFU itself. Potential causes include a failed wiring harness connection, a broken or corroded connector at the EFU 235 interface, a blown fuse or failed relay in the power distribution circuit, or a faulty main control board that is not delivering the required voltage output to the EFU.

Diagnosing this fault requires verifying that the correct supply voltage is reaching the EFU 235 input terminals. Technicians should inspect the associated wiring harness for signs of damage, pinching, or heat stress, and test connector integrity with a multimeter. If wiring and connectors check out, the control board supplying voltage to EFU 235 becomes the primary suspect.

Source: manufacturer service documentation.

Common causes of F4257

  1. 01

    Loose or disconnected wiring harness at EFU 235

    Wiring / connection

    The connector supplying voltage to EFU 235 may have worked loose due to vibration over time. Inspect the harness connector at the EFU 235 module for proper seating and signs of backing out.

  2. 02

    Corroded or damaged connector terminals

    Part replacement

    Moisture or age can corrode the pins at the EFU 235 input connector, creating high resistance or an open circuit. Check terminals for discoloration, oxidation, or physical damage.

  3. 03

    Failed main control board

    Part replacement

    If the control board is not generating or passing the required supply voltage to EFU 235, the fault will trigger even when wiring is intact. This can be confirmed by measuring voltage at the EFU 235 input terminals with the machine powered on.

  4. 04

    Damaged wiring harness

    Part replacement

    A pinched, cut, or heat-damaged wire in the harness between the power supply and EFU 235 can interrupt voltage delivery. Trace the harness along its full routing and look for visible damage or continuity breaks.

  5. 05

    Blown fuse or failed relay in the supply circuit

    Part replacement

    A protective fuse or relay in the voltage supply path to EFU 235 may have failed, cutting off power to the module. Check any fuses associated with the EFU supply circuit on the control board or in the machine's internal fuse block.

See the test procedure for each cause

Frequently asked questions about F4257

What does F4257 mean on a Miele washer?
F4257 indicates a power failure fault where the input voltage to EFU 235 is missing. The EFU 235 is an internal electronic module that requires a specific supply voltage to operate. When the control system detects this voltage is absent, it stops the machine and logs the fault. This points to an issue in the wiring, connectors, or control board supplying that module.
Can I fix F4257 on my Miele washer myself?
Some aspects of this fault are accessible to a knowledgeable DIYer, such as inspecting and reseating harness connectors at the EFU 235 module. However, diagnosing whether the control board is failing to supply voltage requires a multimeter and familiarity with appliance electronics. Replacing a control board or wiring harness is best handled by a qualified technician to avoid further damage.
Is it safe to use my Miele washer while F4257 is showing?
No, you should not attempt to run the washer while this fault is active. The machine has detected a missing voltage supply to an internal electronic component and has shut down as a protective measure. Attempting to bypass or ignore the fault could risk further damage to the electronics or other components.
Will resetting my Miele washer clear the F4257 error?
A reset may temporarily clear the fault display, but if the underlying cause, such as a loose connector, damaged wire, or failed control board, has not been resolved, the error will return. The fault reflects an actual electrical condition that must be corrected for the machine to operate reliably.
How much does it cost to repair a Miele washer with error code F4257?
Repair costs vary depending on the root cause. If the fix is as simple as reseating a connector, the cost may only involve a service call fee, typically in the range of $75 to $150. If a wiring harness or control board replacement is required, total costs including parts and labor can range from $200 to $600 or more, depending on the specific components involved and local labor rates.

Related Miele washer codes

All Miele washer codes
View all 254 Miele washer codes

78,000+ service manuals · 160,000+ error codes · 55+ brands

Get Started

$29/month · Cancel anytime · Or $9.95 3-day pass