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Error code reference

Miele Dishwasher Error Code F18

Flow meter stationary state monitor B3-4; unexpected pulses from the flow meter are detected when the water…

Miele codesMiele dishwasher codes

Flow meter stationary state monitor B3-4; unexpected pulses from the flow meter are detected when the water inlet valve is not activated, indicating the valve may be stuck open.

First step from the service manual

Check the water inlet valve for proper operation (may be stuck in open position).

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

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What F18 means on a Miele dishwasher

The F18 error code on a Miele dishwasher relates to the flow meter stationary state monitor, identified as sensor circuit B3-4. This fault is triggered when the control board detects pulses from the flow meter during a period when the water inlet valve has not been activated. Under normal conditions, the flow meter should register zero flow when the inlet valve is closed. If pulses are detected in this stationary state, the control interprets it as unexpected water movement entering the appliance, which points directly to a valve that is failing to close completely or is stuck in an open or partially open position.

The water inlet valve is an electromechanical solenoid component that opens to allow water into the dishwasher during designated fill cycles and closes completely between cycles. When the valve sticks open due to debris lodged in the seat, a worn solenoid, or a faulty diaphragm, water continues to pass through and spin the flow meter impeller even though the control board has not commanded a fill. This unintended flow is what triggers the F18 fault.

Diagnosis should begin by inspecting the water inlet valve for physical damage, debris, or mineral scale buildup that could prevent full closure. The flow meter itself should also be evaluated, as a sticking or damaged impeller could generate false pulse signals even without actual water flow. Wiring and connector integrity between the flow meter, the inlet valve, and the control board should be checked as well, since intermittent electrical faults can produce spurious sensor readings.

Source: manufacturer service documentation.

Common causes of F18

  1. 01

    Stuck or failed water inlet valve

    Part replacement

    Debris, mineral scale, or a worn diaphragm inside the solenoid valve can prevent it from closing fully, allowing water to trickle through and trigger flow meter pulses when no fill cycle is active. Inspect the valve for blockage or damage and test the solenoid coil for continuity.

  2. 02

    Debris lodged in the valve seat

    Wiring / connection

    Small particles from the water supply can become trapped in the valve seat, holding it partially open. This can sometimes be resolved by cleaning the inlet screen and valve seat, though a damaged seat may require valve replacement.

  3. 03

    Faulty or sticking flow meter impeller

    Part replacement

    If the flow meter impeller is contaminated with scale or debris, it may not spin freely and could generate erratic pulse signals even with minimal or no actual water flow. Inspect the flow meter for obstruction or mechanical damage.

  4. 04

    Wiring or connector fault in the B3-4 circuit

    Wiring / connection

    A damaged wire, corroded connector, or loose terminal between the flow meter sensor and the control board can produce false pulse readings that mimic unexpected water flow. Inspect the harness for visible damage, corrosion, or poor connections.

  5. 05

    Control board fault

    Part replacement

    In rare cases, the control board may incorrectly interpret sensor signals or fail to properly command the inlet valve closed. This is typically considered only after the valve, flow meter, and wiring have been ruled out as the source of the fault.

See the test procedure for each cause

Frequently asked questions about F18

What does F18 mean on a Miele dishwasher?
F18 on a Miele dishwasher indicates that the flow meter stationary state monitor (B3-4) has detected unexpected pulses from the flow meter while the water inlet valve is not activated. This means water is entering the appliance when it should not be, most commonly because the inlet valve is stuck open or failing to close completely. The dishwasher halts operation to prevent overfilling or potential water damage.
Can I fix the F18 error myself?
Some DIYers with appliance repair experience can address this fault by inspecting the water inlet valve for debris or scale buildup, cleaning the inlet screen, and checking the flow meter for obstructions. If the inlet valve solenoid has failed or the diaphragm is worn, the valve will need to be replaced, which requires disconnecting the water supply and working with electrical components. If you are not comfortable working with water supply lines or internal dishwasher components, a qualified technician is recommended.
Is it safe to keep using my dishwasher with an F18 error?
It is not advisable to continue running the dishwasher with an F18 fault active. A stuck-open water inlet valve can cause the appliance to overfill, which may lead to water leakage onto your floor or into surrounding cabinetry. The dishwasher's control system stops operation for this reason, and the underlying issue should be diagnosed and resolved before resuming normal use.
Will resetting the dishwasher clear the F18 error?
Resetting the dishwasher may temporarily clear the F18 code, but the fault will return if the root cause has not been corrected. If the water inlet valve is stuck open or the flow meter is generating false signals, the control board will detect the problem again during the next cycle. A reset should only be used after the underlying issue has been identified and repaired.
How much does it cost to repair an F18 error on a Miele dishwasher?
Repair costs vary depending on the cause and whether you hire a technician or perform the repair yourself. A replacement water inlet valve for a Miele dishwasher typically ranges from around $40 to $120 for the part alone. If a technician is needed, total repair costs including labor can range from approximately $150 to $350 or more depending on your location and the extent of the diagnosis required.

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