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Bosch Washing Machine Error Code E04

Reviewed by the ApplianceErrors Editorial Team · Verified against manufacturer service documentation · Last verified: June 10, 2026
⚠ High Severity 🔧🔧 Moderate DIY

Anti-flood device activated — water detected in base

The most common cause of the E04 error on a Bosch washing machine is water supply hose fitting leaking (~35% of cases); start with: tilt machine to drain base.

💰 DIY cost: $0–$100 👨‍🔧 Pro cost: $150–$380 Save $150+ by doing it yourself
Bosch Washing Machine error code E04 on the display panel
How the E04 code appears on a Bosch washing machine display

What Does Error Code E04 Mean on a Bosch Washing Machine?

Anti-flood device activated — water detected in base.

E04 fires when the AquaStop float switch in the base tray detects standing water and triggers a safety shutdown to prevent flooding. A polystyrene float rises with accumulated water and trips a microswitch, cutting the fill valve and stopping the cycle. Unlike drain or fill fault codes that reflect flow timing, E04 specifically indicates physical water pooling in the base, whether from a supply hose fitting, door seal, loose internal hose, or a cracked tub or pump housing.

Models affected: Bosch front-load washers equipped with the AquaStop anti-flood system, including models such as WAT28400UC and WGA12400UC
What owners report: Owners commonly report this appearing mid-cycle with the machine refusing to restart until the base is dried. A small amount of residual water or a slightly loose inlet hose can be a false trigger, and many find that snugging the supply fitting and letting the unit dry overnight clears the code.

What Causes Error Code E04?

Here are the most common causes in order of frequency. Start with the most likely cause before moving to the next:

  1. 1
    Water supply hose fitting leaking 35% of cases
  2. 2
    Door seal damaged 30% of cases
  3. 3
    Internal hose connection loose 25% of cases
  4. 4
    Tub or pump housing crack 10% of cases

How to Fix Bosch Washing Machine Error Code E04

🔧🔧 Moderate DIY Est. time: 30–60 min
⚡ Safety first: Unplug the appliance before opening any panels or touching internal components.
  1. 1

    Tilt machine to drain base

    Carefully tilt machine forward to drain water from base tray. Power off first.

    ⚠️ Turn off water and power before tilting.
  2. 2

    Inspect supply hose fittings

    Check hose connections at wall and at machine for any weeping.

  3. 3

    Inspect door seal

    Check gasket for tears or detachment.

    🔩 Bosch washer door seal ($30–$75)
  4. 4

    Inspect internal hoses

    Access back panel and check internal hose connections.

How to Reset Error Code E04

Drain base, fix leak, allow to dry. Code clears when float sensor resets.

Note: If the error returns after resetting, the underlying issue has not been resolved. Work through the fix steps above.

Full Bosch washer reset guide → Enter diagnostic mode → Symptom guide: Washer leaking water →

Did this guide fix your appliance?

When to Call a Professional

If no external leak is visible, internal tub or pump housing crack needs professional diagnosis.

Average professional repair cost for this issue: $150–$380

Find Replacement Parts

Use these links to find the exact replacement parts for your Bosch Washing Machine:

🔩
Search PartSelect
Bosch Washing Machine repair parts
🔧
Search RepairClinic
Step-by-step video guides

External links — ApplianceErrors.com is not affiliated with these retailers.

More Bosch Washing Machine Error Codes

E18 Drain time exceeded — water not draining within expected time E02 Door lock failure — cannot lock door for cycle E17 Water intake fault — fill time exceeded F01 Water intake timeout — machine failed to fill within the expected time F02 Heating timeout — water did not reach the target temperature F03 Drain timeout — water did not drain within the expected time

Frequently Asked Questions

Can I keep using my Bosch Washing Machine when error E04 appears? +
It is not advisable. The washing machine may still power on, but running it while E04 is active can worsen the leak fault or damage related parts. Treat it as a soon-as-possible repair.
What most commonly causes E04 on a Bosch Washing Machine? +
Across reported Bosch washing machine repairs, the most frequent is water supply hose fitting leaking (35% of cases), door seal damaged (30%), then internal hose connection loose (25%). Check them in that order before replacing any parts.
E04 keeps coming back after a reset — what should I check next? +
A reset only clears the stored E04 fault; if it returns, the leak problem is still present. Move on to the physical checks — tilt machine to drain base, then inspect supply hose fittings — since the code will reappear until the root cause is resolved. This is a moderate job — a multimeter and some disassembly are usually involved.
How much does it cost to fix Bosch Washing Machine error E04? +
A DIY repair typically runs $0–$100 in parts, versus $150–$380 for a professional service call, so handling it yourself saves around $150. Expect the work to take roughly 30–60 minutes.
Which Bosch Washing Machine models show error E04? +
E04 is documented on Bosch front-load washers equipped with the AquaStop anti-flood system, including models such as WAT28400UC and WGA12400UC. Other units sharing the same control platform can display it too, so the fixes here generally transfer across the series.

Sources & References

Content verified against manufacturer service documentation. Last verified: June 10, 2026.

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