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Error code reference

Miele Washer Error Code F4027

Liquid dispensing fault during final rinse; valve Y39 defective, B1/1 level switch or connection leads…

Miele codesMiele washer codes

Liquid dispensing fault during final rinse; valve Y39 defective, B1/1 level switch or connection leads defective, or tap closed.

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What F4027 means on a Miele washer

F4027 is a liquid dispensing fault that occurs specifically during the final rinse cycle. This error points to a failure in the system responsible for delivering water or liquid (such as fabric softener) into the drum during the final rinse phase. The primary suspect is valve Y39, which is the solenoid valve controlling liquid flow at this stage of the cycle. When Y39 fails to open or close correctly, water cannot enter the machine as expected, triggering the fault code.

The B1/1 level switch is also directly implicated in this fault. This pressure or float-based switch monitors the water level inside the drum and communicates that information to the control board. If the B1/1 switch is faulty or if the connection leads between the switch and the control board are damaged, corroded, or loose, the machine cannot confirm proper water levels during the final rinse, which causes it to register a dispensing fault. Wiring harness inspection between these components is an important diagnostic step.

A closed or restricted water supply tap is the simplest possible cause and should be ruled out first. If the tap supplying water to the machine is partially or fully closed, insufficient water pressure will prevent the dispenser system from functioning, even if all electrical components are intact. Technicians should verify full water supply before proceeding to component-level diagnostics on valve Y39 or the B1/1 level switch.

Source: manufacturer service documentation.

Common causes of F4027

  1. 01

    Closed or restricted water supply tap

    Wiring / connection

    If the water supply tap connected to the washer is partially or fully closed, the machine cannot draw enough water for the final rinse. Check that the tap is fully open and that water pressure is adequate.

  2. 02

    Defective valve Y39

    Part replacement

    Valve Y39 is the solenoid valve that controls liquid flow during the final rinse. If it fails electrically or mechanically, water will not dispense correctly. Testing involves checking the valve coil for correct resistance and confirming it actuates when voltage is applied.

  3. 03

    Faulty B1/1 level switch

    Part replacement

    The B1/1 level switch monitors water level inside the drum and reports back to the control board. A defective switch may send incorrect signals, causing the machine to believe the dispensing cycle has failed even when water is present.

  4. 04

    Damaged or loose connection leads to B1/1 or Y39

    Wiring / connection

    Corroded, broken, or disconnected wiring between the control board and either the B1/1 level switch or valve Y39 can interrupt signals and trigger this fault. Inspect the wiring harness at both component connectors for visible damage or poor seating.

See the test procedure for each cause

Frequently asked questions about F4027

What does F4027 mean on a Miele washer?
F4027 indicates a liquid dispensing fault that occurs during the final rinse cycle. The error points to a problem with valve Y39, the B1/1 water level switch, the wiring connecting these components, or a closed water supply tap. The machine has detected that it cannot properly deliver liquid during the final rinse and has stopped the cycle to prevent incomplete washing.
Can I fix F4027 on my Miele washer myself?
Some causes of F4027 are simple to address without professional help. Start by confirming the water supply tap behind the machine is fully open and that household water pressure is normal. Inspecting accessible wiring connections for obvious damage is also within reach for a confident DIYer. However, replacing valve Y39 or the B1/1 level switch involves working with internal components and electrical connections, which is better handled by a qualified technician.
Is it safe to keep using my Miele washer when F4027 appears?
It is not recommended to continue running the washer while F4027 is active. The error indicates the final rinse could not complete properly, meaning laundry may not be rinsed of detergent residue. Continued use could also stress other components if the underlying cause involves a faulty valve or water level sensor.
Will resetting the washer clear the F4027 error?
Resetting the machine may temporarily clear the error code, but it will return if the underlying cause has not been resolved. If the fault is triggered by a closed water tap, simply opening the tap and restarting the cycle may clear it permanently. Faults caused by a defective valve Y39 or B1/1 level switch will require component repair or replacement before the code clears for good.
How much does it cost to repair a Miele washer showing F4027?
Repair costs vary depending on the root cause. If the fix is as simple as opening a water supply tap, there is no parts cost. Wiring repairs may cost between $75 and $200 in labor. Replacing valve Y39 or the B1/1 level switch on a Miele washer typically runs between $150 and $400 depending on parts pricing and local labor rates.

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