F21
Miele Washing Machine
Severity: ModerateWhat Does This Error Mean?
F21 means the washing machine's heating system has a fault. The water is not reaching the required temperature. Common causes are a failed heating element or NTC temperature sensor.
Affected Models
- Miele W1
- Miele WDB020
- Miele WDB030
- Miele WCI320
- Miele WCI860
- Miele WDD030
Common Causes
- Heating element burned out
- NTC (temperature sensor) faulty
- Wiring harness to the heater damaged
- Control board not sending power to the heater
How to Fix It
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Run a hot wash and feel the drum glass partway through.
If the water never warms up, the heater is likely at fault. A cold drum after 20 minutes on a 60°C wash confirms a heating fault.
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Reset the machine.
Turn off at the mains for 5 minutes. Restart and try again — occasionally a sensor gives a false reading.
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Test the NTC temperature sensor (engineer required).
The NTC should read around 1200–1500 Ohms at room temperature. A reading of 0 or infinity indicates a failed sensor.
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Test the heating element (engineer required).
A working heating element reads 20–30 Ohms. Open circuit (no reading) means it has burned out and needs replacing.
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Book a Miele service engineer if needed.
Heating element replacement on a Miele is a straightforward repair. Miele's own engineers are familiar with this fault — it is one of the more common repairs.
Frequently Asked Questions
Will F21 damage my clothes?
No — if the machine cannot heat, it typically washes at cold water temperature instead. Your clothes will come out clean (especially on modern detergents) but not sanitised at the set temperature.