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Bosch Washing Machine Error Code F21

Reviewed by the ApplianceErrors Editorial Team · Verified against manufacturer service documentation · Last verified: July 19, 2026
⚠ High Severity 🔧🔧🔧 Advanced DIY Also shown as: E21

Motor fault — drum not spinning or motor running abnormally

The most common cause of the F21 error on a Bosch washing machine is drum jammed by a foreign object (~35% of cases); start with: check for a foreign object.

💰 DIY cost: $10–$250 👨‍🔧 Pro cost: $180–$450 Save $170+ by doing it yourself
Bosch Washing Machine error code F21 on the display panel
How the F21 code appears on a Bosch washing machine display

What Does Error Code F21 Mean on a Bosch Washing Machine?

Motor fault — drum not spinning or motor running abnormally.

The control monitors motor speed feedback (typically via a tachometer or Hall sensor) and fires F21 when the drum fails to reach or hold the commanded speed. This can mean the motor draws current but the drum won't turn, or the controller sees no rotation signal at all. Unlike drain-related codes such as F04 or E18, F21 points squarely at the drive path — a mechanical jam, worn carbon brushes, failed windings, or the motor control electronics.

Models affected: Bosch front-load washers, including brush-motor models such as the WAT28400UC; note that some newer units like the WGA12400UC use brushless motors where worn brushes do not apply
What owners report: Owners commonly report F21 appearing at the start of a spin cycle, sometimes after a bulky item or stray object shifts into the drum. A quick win many describe is unplugging, turning the drum by hand to check for jams, and clearing anything caught between drum and tub before assuming a motor failure.

What Causes Error Code F21?

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

  1. 1
    Drum jammed by a foreign object 35% of cases
  2. 2
    Worn carbon brushes 30% of cases
  3. 3
    Drive motor winding failure 20% of cases
  4. 4
    Motor control board fault 15% of cases

How to Fix Bosch Washing Machine Error Code F21

🔧🔧🔧 Advanced DIY Est. time: 1–3 hours
⚡ Safety first: Unplug the appliance before opening any panels or touching internal components.
  1. 1

    Check for a foreign object

    Unplug the machine and try to turn the drum by hand; resistance indicates a jam.

    ⚠️ Unplug before reaching into the drum.
  2. 2

    Inspect carbon brushes

    Worn brushes (under 10–15 mm) must be replaced on brush-motor models.

    🔩 Bosch washer carbon brushes ($10–$30)
  3. 3

    Test motor windings

    Measure winding resistance with a multimeter.

    🔩 Multimeter
  4. 4

    Replace the motor or control board

    If brushes are fine and windings are bad, replace the motor.

    🔩 Bosch drive motor ($100–$250)

How to Reset Error Code F21

Unplug 5 minutes and restart; if drum is jammed, clear the obstruction first.

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 not spinning →

Did this guide fix your appliance?

When to Call a Professional

If carbon brushes and motor windings test good, replace the motor control board.

Average professional repair cost for this issue: $180–$450

Related Error Codes

F04
Motor fault — drive motor not running correctly
⚠ High Severity
F43
Drum not turning — motor jammed, worn brushes, or motor fault
⚠ High Severity
E18
Drain time exceeded — water not draining within expected time
⚠ High Severity

Same Code on Other Brands

Error code F21 appears on these other brands too. See every brand that shows F21 →

Whirlpool logo
Whirlpool Washing Machine F21
Long drain — water not draining in the expected time
Kenmore logo
Kenmore Washing Machine F21
Slow drain — pump is draining but too slowly

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

E02 Door lock failure — cannot lock door for cycle E17 Water intake fault — fill time exceeded E04 Anti-flood device activated — water detected in base 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 F21 appears? +
It is not advisable. The washing machine may still power on, but running it while F21 is active can worsen the motor fault or damage related parts. Treat it as a soon-as-possible repair.
What most commonly causes F21 on a Bosch Washing Machine? +
Across reported Bosch washing machine repairs, the most frequent is drum jammed by a foreign object (35% of cases), worn carbon brushes (30%), then drive motor winding failure (20%). Check them in that order before replacing any parts.
F21 keeps coming back after a reset — what should I check next? +
A reset only clears the stored F21 fault; if it returns, the motor problem is still present. Move on to the physical checks — check for a foreign object, then inspect carbon brushes — since the code will reappear until the root cause is resolved. This is an advanced repair involving deeper disassembly or electrical testing.
How much does it cost to fix Bosch Washing Machine error F21? +
A DIY repair typically runs $10–$250 in parts, versus $180–$450 for a professional service call, so handling it yourself saves around $170. Expect the work to take 1–3 hours.
Which Bosch Washing Machine models show error F21? +
F21 is documented on Bosch front-load washers, including brush-motor models such as the WAT28400UC; note that some newer units like the WGA12400UC use brushless motors where worn brushes do not apply. 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: July 19, 2026.

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