What this error means
The E21 error code on your Bosch washing machine means a motor fault has been detected — the machine has found a problem with the motor itself and has stopped the cycle to prevent damage.
The E21 error code indicates that the machine has detected a fault directly with the main drive motor. This is distinct from E02 (which is a motor control electronics fault) — E21 points to a physical or electrical fault within the motor itself. This includes worn carbon brushes on brush-type motors, a short circuit in the motor windings, a motor that has seized (stopped spinning), or a fault with the motor's tachometer (the small component that tells the machine how fast the motor is spinning). On newer Bosch machines with inverter (brushless) motors, E21 can also point to a fault within the inverter motor unit. As with all motor faults, a power reset is the first step before any further investigation.
What you'll need first
Affiliate links — we may earn a small commission at no extra cost to you.
Step-by-step
Symptoms to look for
- E21 displayed on the control panel
- Drum failing to rotate or rotating intermittently
- Loud grinding, clicking, or buzzing from the motor area
- Burning smell during a cycle
- Machine starts normally then stops part-way through the wash or spin phase
Diagnostic steps
Unplug the machine and leave it disconnected for at least 5 minutes. Motor thermal protection can trigger E21 if the motor has been running hot — a rest period allows it to cool and the control board to reset. Plug back in and try a short cycle.
Remove all items from the drum completely and run an empty rinse-and-spin cycle. If the drum turns freely with no load, overloading was likely the cause. If the drum does not turn at all, or E21 appears immediately, the fault is in the motor or tachometer.
On Bosch washing machines manufactured before approximately 2012, the drive motor uses carbon brushes that wear down over time. When they become too short, the motor loses power and the machine stops. Brushes can be accessed from the back of the machine after removing the back panel. They slot into the motor housing and should be at least 5–6 mm long to function correctly. Replacement brushes cost £5–£15 and are available online.
Check your machine's model number (on the data plate inside the door frame, or on the back panel) and search online to confirm whether it uses a brush motor or a brushless inverter motor. Inverter motor models will usually say "EcoSilence Drive" or "iQdrive" on the front panel or in the product description. Brush replacement is only relevant for brush motor models.
The tachometer (tacho) is a small sensor attached to the motor that measures the drum rotation speed. A faulty tacho can cause E21 even when the motor itself is healthy. An engineer can test the tacho with a multimeter — a faulty tacho is often cheaper to replace than a new motor.
If the error persists after a power reset, with an empty drum, on multiple programmes, the fault is most likely a worn motor, a faulty tachometer, or in some cases a fault on the motor wiring harness. All of these require an engineer with appropriate testing equipment.
When to call an engineer
- E21 persists after power reset with an empty drum
- Burning smell detected during operation
- Drum not rotating on any programme
- Motor makes grinding or clicking sounds consistently
- Tachometer or motor wiring fault confirmed with a multimeter
Frequently asked questions
What does E21 mean on a Bosch washing machine?
What is the difference between E21 and E02 on a Bosch washing machine?
Can I fix Bosch E21 myself?
How much does motor replacement cost on a Bosch washing machine?
Why does my Bosch washing machine smell of burning with E21?
🎯 What is most likely causing your Bosch E21 error?
⚠️ Estimates based on common faults — not a guaranteed diagnosis. Always verify before ordering parts.
Parts you may need
Enter your model number to filter results to your exact machine
Usually found on a label inside the door frame or on the back panel of the machine.
| Part | Approx. UK Cost | Find it |
|---|---|---|
| Motor carbon brushes | £5 - £10 | 🛒 Amazon UK → |
| Tachometer coil | £15 - £40 | 🛒 Amazon UK → |
| Tachometer Coil & Brushes | £5 - £10 | 🏷️ eBay UK → |
ℹ️ Prices are approximate. Always check the part number matches your model before ordering. Not sure of your model number? Find out how to locate it here.