EN

Severity: Moderate

Bosch Washing Machine Error F21 – Motor Fault – Drum Won't Turn

The motor was powered but the drum didn't turn as expected – often worn carbon brushes or a jammed object.

At a glance

Severity: 3/5 – Moderate3/5

Severity: Moderate

Meaning
Motor Fault – Drum Won't Turn
Typical repair cost
$0–$650
DIY difficulty
Moderate

F21 (E:21 on newer displays) is Bosch's drive fault: the control board switched the motor on, but the speed signal from the motor's tacho coil was missing or made no sense, so the drum either stood still or ran away. On the Nexxt 300/500/800 full-size front loaders and older Axxis compacts the motor is a brushed universal motor, and after many loads its two carbon brushes simply wear down. A bra underwire or coin wedged between the drum and the outer tub can stall the drum just as well, so check that it turns freely before buying parts. When the drum spins easily and the brushes look fine, the tacho, the motor harness or the motor-control section of the main board are next.

How it looks on the display

Bosch Washing Machine display showing error F21

Model families & display variants

Model familyShowsNote
Nexxt 300/500/800 Series full-size front loadersF21The fault is kept in memory and can reappear after power-up until it is cleared in service mode.
Older 24-inch Axxis compact washersF21Same drive fault with the F prefix.
Current 24-inch 300/500/800 Series compactsE:21The manual lists it among other messages: switch off, restart once, call service if it repeats.

Safety first · Consult a professional

Unplug the washer before turning the drum by hand or opening the back panel – the motor plug carries line voltage. If water is standing in the drum, drain it first.

  • Unplug the appliance or switch off the breaker before opening any panel. Mains voltage can kill.

Symptoms

  • F21 or E:21 on the display and the cycle has stopped
  • Water fills, but the drum never starts tumbling
  • A short hum or click from the lower back, then the code
  • Drum jerks a few inches and stops
  • Black carbon dust on the motor or on the floor under the washer
  • Code shows up only now and then, usually when the spin starts

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. Carbon brushes worn down on the brushed drive motor 38%
  2. Underwire, coin or hairpin jammed between drum and outer tub 16%
  3. Loose or corroded plug at the motor, or a harness chafed by vibration 12%
  4. Tacho coil inside the motor open or giving an erratic signal 12%
  5. Motor-control circuit on the main control board 12%
  6. Damaged motor winding or burnt commutator 7%
  7. Drive belt thrown off the pulley 3%

Fix it step by step

Diagnostic flow: F211One clean restart2Turn the drum by hand3Fish out foreign objects4Inspect the carbon brushes5Measure at the motor plug6Test after the repair

  1. One clean restart

    Turn the selector to Off, unplug for three minutes, plug back in and run Rinse/Spin. If the drum turns normally, a tangled blanket or a brief supply dip may have caused a one-off stop.

  2. Turn the drum by hand

    Unplug, drain any water, open the door and rotate the drum both ways. It should move smoothly with a light, even drag from the motor. Scraping, a hard stop at one point or a rattle means something is caught between drum and tub.

    Tools: Gloves, Flashlight

  3. Fish out foreign objects

    Shine a light through the drum holes; an underwire poking through can be pulled out with needle-nose pliers. Small items that dropped into the tub usually end up at the drain pump, which you can reach behind the service cover at the bottom front.

    Tools: Flashlight, Pliers

  4. Inspect the carbon brushes

    Pull the washer out, remove the back panel and locate the motor under the tub. Unclip and unscrew the two brush holders on its sides. Replace both brushes as a pair if either is down to roughly half an inch, chipped, or stuck in its holder.

    Tools: Screwdriver, Flashlight, Gloves

  5. Measure at the motor plug

    With the plug off, measure across the brush circuit: a few ohms is normal, an open reading or a jumping value means the brushes aren't making contact or the commutator is damaged. The two tacho pins should give a steady resistance; an open circuit points to the tacho.

    Tools: Multimeter

  6. Test after the repair

    Reassemble, run Rinse/Spin empty and then a small load. New brushes need a few cycles to bed in, so avoid maximum spin for the first washes.

How to reset F21

  1. Turn the cycle selector to Off and unplug the washer for a few minutes.
  2. Plug in, choose Spin or Rinse/Spin and press Start.
  3. If the drum turns and the code stays away, run a normal load and watch the first minutes.
  4. If F21/E:21 comes back at once, stop retrying – restarts won't cure worn brushes, and some models keep the fault stored until service clears it.

Where the parts are

Washing machine: drain filter, pump and door lock – F2112345678
Washing machine: drain filter, pump and door lock
  1. 1Door lock
  2. 2Water inlet valve
  3. 3Water level sensor
  4. 4Filter
  5. 5Drain pump
  6. 6Motor
  7. 7Heating element
  8. 8Temperature sensor

Repair options & costs

RepairDIY?Estimated cost
Remove a jammed object (reachable through drum or pump) Yes $0–$10
Carbon brush pair, DIY install Yes $30–$70
Motor harness or plug repair by a technician No $150–$260
Main control board replacement No $300–$550
Drive motor replacement No $380–$650

Rough US estimates; technician call-out fees vary by region. Not a quote.

When to call a technician

Call Bosch service or an appliance technician if the drum turns freely and new brushes don't clear the code, if you smell burning or see scorch marks on the motor, or if the code appears on a model with a brushless motor. Stacked or closet installs usually need two people to pull the washer out safely.

Frequently asked questions

Can I keep using the washer if F21 only appears now and then?

An occasional F21 usually means the brushes are close to the end. Every failed start stresses the motor-control circuit, so replace the brushes soon instead of pushing through.

Do all Bosch washers have carbon brushes?

No. Many newer Bosch washers use a brushless EcoSilence Drive motor. On those, F21/E:21 points to a jam, the motor electronics or the motor itself – there are no brushes to change.

I replaced the brushes and still get F21 – why?

Check that the brushes slide freely and that the plug is fully seated. Some Bosch models also keep the fault stored until it is cleared through the service program, which a technician can do.

Is a motor fault covered by warranty?

Some Bosch US models carry extended coverage on the drive motor and circuit boards beyond the basic warranty. Check the warranty statement in your manual before paying for a motor or board.

Sources