The Bosch washing machine F21 error is a motor fault: the machine told the drum to turn and the motor did not respond as expected, so it stopped the programme. A few causes are simple checks you can make safely, but most F21 faults end with a visit from an engineer, and this guide shows you where that line sits.
Quick answer: F21 on a Bosch washing machine means a motor or drum drive fault. Common causes are an overloaded or jammed drum, worn carbon brushes or a motor fault. It is safe to switch off, wait a few minutes and restart once. If F21 returns, do not keep resetting: book a qualified engineer.
What Does the Bosch F21 Error Code Mean?
F21 means the motor could not turn the drum at the speed the control module asked for. Depending on the display, the same fault can show as E21 or E:21. Bosch does not publish an F21 page on its UK support site, so this meaning comes from independent appliance retailers and repair specialists who agree on it, and you should confirm it in your model’s instruction manual.
A current Bosch instruction manual we checked takes the same line on motor faults in general: it tells owners to contact customer service rather than attempt a repair. On Bosch machines with a brushed motor, power reaches the spinning part of the motor through a pair of carbon brushes, which wear down over years of use. When they get too short, the motor loses power or stops, and an F21 is one of the ways the machine reports it.
What Causes the F21 Error?
- Worn carbon brushes. A common cause on machines with brushed motors. Bosch’s guide to a drum that is not turning says worn brushes need a repair by a trained and qualified Bosch engineer.
- Overloaded or jammed drum. Too much laundry, a heavy bundle, or an item such as an underwired bra or coin caught between the drum and the outer tub can stop the drum turning freely.
- Transport bolts left in. On a newly installed machine, the bolts that lock the drum for delivery stop it moving. Bosch’s installation guide says all four must be removed before first use.
- Motor wiring or connector fault. A loose plug, damaged wire or burnt connection at the motor.
- Speed sensor (tacho) fault. If the sensor that reports drum speed fails, the module cannot see the drum turning.
- Motor or control module failure. Only an engineer can diagnose and replace these parts.
Some websites describe F21 as a drain fault. That is not what the code means on Bosch machines. Drainage problems have their own code, E18 or F18, covered in the table below.
How Do You Fix the Bosch F21 Error Yourself?
These checks are safe for a homeowner and rule out the simple causes before you pay for a visit.
- Reset once. Switch the machine off at the programme dial, wait about 3 minutes, then switch on and choose a short programme. A one off glitch may clear.
- Switch off and unplug. If the error returns, turn the machine off and unplug it at the wall before you touch the drum, filter or hoses.
- Empty any water. If water is left in the drum, the door may stay locked. Bosch manuals warn that water from a hot wash can scald, so let it cool first. Then lay towels down, open the service flap at the bottom front, put a shallow tray under the emergency drain hose and let the water out.
- Reduce the load. Once the door opens, take out some of the laundry, especially heavy or bulky items, and spread the rest evenly.
- Turn the drum by hand. With the machine still unplugged and the drum empty, turn the drum slowly. It should move freely and quietly. If it grinds, catches or will not move, something may be trapped or a part may be damaged: stop and call an engineer.
- Check the drain pump filter. While the flap is open, unscrew the filter, remove any coins, buttons or wires, rinse it and screw it back firmly. A trapped object can sometimes come from the drum.
- Check the transport bolts on a new install. If the machine was fitted recently and F21 appeared on the first washes, look at the back for the four transport bolts. If they are still in place, stop using the machine and have the installer remove them.
- Test with a small load. Plug back in and run a short programme with a half load. If F21 appears again, the fault is inside the machine.
Safety: Stop here if F21 comes back. Carbon brushes, the motor, its wiring, the speed sensor and the control module all sit behind the casing and involve mains electricity. Do not remove the back panel, test the motor or fit brushes yourself: book a Bosch engineer or a qualified appliance technician. Always unplug the machine before touching the filter or hoses.
When Should You Call an Engineer?
- F21 returns after a reset and a smaller load.
- The drum will not turn by hand, grinds or feels rough.
- The drum stops when filled with water or during the spin. Bosch links this to worn carbon brushes.
- You notice a burning smell, sparks, or the circuit breaker trips.
- The machine is under warranty, as opening it yourself may affect your cover.
Bosch offers engineer repairs in and out of warranty, and independent repairers also service Bosch machines. Prices depend on the part and your area, so ask for a quote. If you are weighing a repair against a new machine, our electricity cost calculator helps you compare what each wash costs to run.
Related Bosch washing machine codes
These meanings are taken from Bosch’s own support pages. Codes vary between model ranges, so check your manual.
| Code | Meaning | Who fixes it |
|---|---|---|
| F21 / E21 | Motor fault (not published by Bosch, confirm in manual) | Reset once, then an engineer |
| E16 / F16 | Door not locked properly | You: free trapped laundry, close firmly |
| E17 / F17 | Water inlet filters blocked or water pressure too low | You: clean filters; a plumber for low pressure |
| E18 / F18 | Drain pump blocked or drain hose blocked or kinked | You: clean pump filter, check hose |
| E23 / F23 | Leak, or water in the base plate | Turn off the tap, then an engineer |
| E32 / F32 | Imbalance detected | You: mix large and small items |
| E33 / F33 | Detergent foam detected | You: use less detergent |
How Can You Stop the F21 Error Coming Back?
- Respect the load limit. Your manual gives the maximum load for each programme. Overfilling makes the motor work harder on every spin.
- Empty pockets and use wash bags. Coins and bra wires are the usual items that jam between drum and tub.
- Mix large and small items so the load balances, as Bosch advises, which reduces strain during spin.
- Keep the machine level and stable so the drum runs smoothly.
- Clean the drain pump filter regularly to catch small objects before they cause damage.
- Act on early signs. A drum that hesitates, spins weakly or smells hot is worth an engineer’s check before it stops completely.
You can find more household tools in our home calculators, and read how our calculators work to see the sources and assumptions we use.
Bosch Washing Machine F21 Error FAQs
How do I reset F21 on a Bosch washing machine?
Switch the machine off at the programme dial, wait about 3 minutes and switch it back on, then start a short programme with a smaller load. If F21 returns, the fault is real. Do not keep resetting it; book a qualified engineer instead.
Is F21 the same as E21 on a Bosch washing machine?
Usually, yes. Appliance retailers and repairers treat E21 and E:21 as the same motor fault shown in a different display format. Check your instruction manual to confirm the code for your model.
Why will my Bosch washing machine door not open after F21?
The door usually stays locked while water is in the drum. Unplug the machine, let hot water cool, then drain it through the emergency hose behind the service flap at the bottom front. Never force the door, as that can break the lock.
Can worn carbon brushes cause F21?
Yes. Worn carbon brushes are a common cause on Bosch machines with brushed motors. Bosch says a drum that stops when filled with water or during spin can indicate worn brushes, which need a repair by a trained and qualified engineer.
Is F21 a drain pump fault?
No. F21 relates to the motor and drum drive. Bosch uses E18 or F18 for a blocked drain pump or a kinked or blocked drain hose. Cleaning the pump filter is still worth doing, as it can catch objects that jam the drum.
Is it worth repairing a Bosch washing machine with an F21 error?
It depends on which part has failed, so ask the engineer to diagnose the fault, get a written quote and weigh it against the age and condition of the machine.
Checked October 2026. Sources: Bosch UK: Washing machine drum is not turning, Bosch UK: How to install a washing machine, Bosch UK: E18 error, Bosch UK: E16 error, Bosch UK: E23 error, Bosch US: Washer error codes. F21 meaning cross checked with Coolblue (Bosch and Siemens washing machine errors) and Domex UK (Bosch washing machine error codes explained).
