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F18

Bosch F18 on washing machine: drain hose blocked or kinked

Verified with sources1 sourceReviewed Oct 3, 2026
Technician coming? See the 2 steps they must show you
Front-loading washing machine
Dany kgPublic domainImage source

Risk level

Medium

Proceed carefully and stop if the check is unclear.

Urgency

Medium

Quick answer

Your Bosch washer shows F18 because the drain hose is blocked or kinked. Set the programme to OFF, unplug the washer and check the hose; if it continues, clean the pump carefully: the water may be very hot.

Safety first

Stop and check this first

  • Water and electricity: do not open the pump cover with the washer plugged in or with water pooling near the socket.
  • Bosch warns that leaking water may be very hot, with a risk of scalding. Set the programme to OFF and unplug the washer before removing the hose or opening the pump.

Safe checks you can perform

  • Hose without kinks
  • Clean hose and siphon
  • Clean the pump

Leave these tasks to a qualified professional

  • Do not attempt this professional task: Drain diagnosis
  • Do not attempt this professional task: Drain and leak test

What a technician must be able to justify

A technician is coming

These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.

These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.

  1. Drain diagnosis

    What they doIf the hose, siphon and pump are clean, Bosch service checks the drain system with the washer unplugged.

    They must show youthe fault reproduced with a clean hose and pump.

    In writingthe cause found, the reference of any replaced part and why.

  2. Drain and leak test

    What they doAfter the repair, the technician runs DRAIN and checks the pump cover does not leak.

    They must show youwater draining without F18 and without leaks.

    In writingthe test result.

Before accepting a part or repair

Nothing has been shown yet. Do not accept a part swap based on the code alone.

Checks and evidence, step by step

Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.

  1. 1

    Hose without kinks

    No special tools

    Procedure

    Who:
    you.
    How:
    set the programme to OFF, unplug the washer and check the drain hose is installed without kinks, as Bosch instructs.
    Result that matters:
    a straight hose to the drain.
    If it was kinked:
    straighten it; that was the likely cause.
    If it is straight:
    move on to cleaning the hose and siphon.
    Evidence to keep:
    a photo of the hose.

    Evidence: Bosch Washer Error Codes

  2. 2

    Clean hose and siphon

    Tools required

    Procedure

    Who:
    you, with the washer unplugged.
    How:
    loosen the hose clip at the siphon, carefully remove the hose and any residual water, clean the hose and the siphon spigot and, holding the hose in a bucket, select the DRAIN programme, as Bosch instructs. Reconnect and check for leaks.
    Result that matters:
    water flowing strongly into the bucket.
    If it flows well:
    the blockage was in the hose or the siphon.
    If it does not flow:
    move on to the pump.
    Evidence to keep:
    a photo of what you removed.

    Unplug the washer before loosening anything. The water may be very hot: let it cool and protect the floor.

    Evidence: Bosch Washer Error Codes

  3. 3

    Clean the pump

    Tools required

    Procedure

    Who:
    you, with the washer unplugged and the water cool.
    How:
    open the service flap, drain the water through the drainage hose by slowly removing the pump cover, clean the interior and thread and check the impeller turns, as Bosch instructs. Screw the cover on firmly, pour one liter of water into the detergent dispenser, check for leaks and run DRAIN.
    Result that matters:
    an impeller that turns freely and a cover with no leaks.
    If there was an object and it now drains:
    that was the cause.
    If the impeller turns and F18 stays:
    call Bosch service with the exact code.
    Evidence to keep:
    a photo of the object removed and the dry cover.

    Always unplug before opening the service flap and remove the pump cover slowly: Bosch warns the water may be very hot. Do not take apart anything beyond the pump cover.

    Evidence: Bosch Washer Error Codes

Where this code applies

A code is meaningful only inside the right product and version context.

Primary scope

System
Appliances
Brand
Bosch
Product type
Washing machines

Known code variants

  • anomalía F18 Miele
  • anomalie F18 Miele
  • Bosch F18 lavadora
  • Bosch F18 washer
  • Bosch lavadora no desagua F18
  • Bosch washer F18 error
  • Bosch washer not draining F18
  • code erreur F18 lave-linge Siemens
  • code erreur F18 lave-vaisselle Miele
  • codice E18 Siemens
  • código E18 Siemens
  • E00-18
  • erreur E18 Siemens
  • error F18 lavadora Bosch
  • error F18 lavadora Siemens
  • error F18 lavavajillas Miele
  • errore F18 lavastoviglie Miele
  • errore F18 lavatrice Siemens
  • F18 Siemens
  • Fehlercode F18 Miele
  • guasto F18 Miele
  • Miele dishwasher F18
  • Miele F18
  • Miele fault F18
  • Miele Geschirrspüler Fehler F18
  • Siemens E18
  • Siemens F18
  • Siemens Fehlercode E18
  • Siemens Waschmaschine Fehler F18
  • Siemens washer F18
  • Siemens washing machine E18

What it means

Bosch defines E18 and F18 as drain hose blocked or kinked: water does not leave as the control expects. Bosch documents it on its US washer page. Its steps, always with the programme set to OFF and the washer unplugged, are to check the hose has no kinks, clean it together with the siphon spigot and, if it continues, clean the pump: the impeller must be able to turn. Bosch warns that the water may be very hot, with a risk of scalding. The code alone does not prove the pump is faulty.

Warnings and stop conditions

  • Mediumeditorial warning

    Water and electricity: do not open the pump cover with the washer plugged in or with water pooling near the socket.

    Evidence: Bosch Washer Error Codes

  • Highsource verified

    Bosch warns that leaking water may be very hot, with a risk of scalding. Set the programme to OFF and unplug the washer before removing the hose or opening the pump.

    Evidence: Bosch Washer Error Codes

Symptoms and causes

Probable causes · in order

  • Kinked hoseCommon

    The drain hose is folded behind the washer. You see it when you move the washer out, and the code clears once it is straightened.

    Evidence: Bosch Washer Error Codes

  • Blocked hose or siphonPossible

    The hose is straight but there is debris inside it or in the siphon spigot. Bosch says to remove it and clean both.

    Evidence: Bosch Washer Error Codes

  • Blocked drain pumpPossible

    Hose and siphon are clean but water still does not leave. An object in the pump stops the impeller turning, following Bosch steps.

    Evidence: Bosch Washer Error Codes

Virtual technician

Does F18 still appear after these checks?

Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.

Start diagnosis

Sources and technical references

  1. 1

    Bosch Washer Error Codes

    Bosch · 2026 · official_doc

Sources: Bosch Washer Error Codesreviewed 2026-10-03 · verified

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