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Severity: Moderate

Miele Washing Machine Error F20 – Causes & Fix

The Miele couldn't heat the wash water in the time allowed. Usually a failed heater or temperature sensor.

At a glance

Severity: 3/5 – Moderate3/5

Severity: Moderate

Meaning
Heating Fault – Water Not Reaching Temperature
Typical repair cost
$0–$850
DIY difficulty
Hard

F20 (shown as 'Heating fault' on text displays) means the washer ran its heating phase but the temperature sensor didn't report the target temperature within the time the program allows. Miele's washers wait until the set temperature is actually reached before continuing, so when the heater fails the program stalls and ends with this code. The heating element itself is the most frequent culprit, followed by the temperature sensor and the wiring or relay that switches the heater. Apart from one power reset, this is a repair for a Miele technician.

How it looks on the display

Miele Washing Machine display showing error F20

Model families & display variants

Model familyShowsNote
W1 washers with text display (incl. US compact models)F20Shown with the words 'Heating fault'; the program is stopped.
Connected W1 modelsF20The heating fault is also sent to the Miele app.
Washer-dryersF20Combo units use the same code for the wash heater; the drying heater has its own messages.

Safety first · Consult a professional

The heater works at mains voltage and sits inside the tub. Don't open the cabinet; if the breaker or GFCI trips when the washer heats, leave it unplugged until it has been checked.

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

Symptoms

  • F20 or 'Heating fault' on the display, often well into the cycle
  • Laundry and door glass stay cold on warm or hot programs
  • Program time counts much longer than normal before the fault
  • Cold or 'Cold' setting programs finish without problems
  • Breaker or GFCI outlet trips as soon as heating starts

Possible causes

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

  1. Heating element burned out (open circuit) 36%
  2. Temperature sensor (NTC) faulty or reading wrong 18%
  3. Loose or corroded connector at the heater 12%
  4. Heater relay or control electronics fault 12%
  5. Element leaking to ground and tripping the breaker or GFCI 10%
  6. Heavy scale on the element from hard water 8%
  7. One-off glitch after a power interruption 4%

Fix it step by step

Diagnostic flow: F201Do Miele's power reset2Check breaker and GFCI3Confirm the washer isn't heating4Note when the code appears5Book Miele service

  1. Do Miele's power reset

    Switch the washer off, unplug it (or switch off the breaker) and wait at least two minutes. Reconnect, switch on and restart the program once.

  2. Check breaker and GFCI

    See whether the breaker or a GFCI outlet has tripped. If it trips again when the washer starts heating, stop using it – that pattern points to an element leaking to ground.

    Tools: Flashlight

  3. Confirm the washer isn't heating

    Run a short program at 104 °F (40 °C). After about 20 minutes, carefully touch the door glass: it should feel noticeably warm. Cold glass with F20 at the end confirms a heating problem.

  4. Note when the code appears

    Write down whether F20 shows only on hot programs, on every warm program or randomly. This saves the technician time deciding between heater, sensor and electronics.

  5. Book Miele service

    The technician measures the element (a healthy one reads in the low tens of ohms, a failed one reads open), checks the sensor and the relay on the control board, and reads the fault memory.

    Tools: Multimeter

How to reset F20

  1. Switch the washer off and unplug it for at least two minutes.
  2. Plug back in, switch on and select the program again.
  3. Start it: if F20 does not return and the water gets warm, it was a one-off glitch.
  4. If F20 comes back, don't keep resetting – book a repair.

Where the parts are

Washing machine: drain filter, pump and door lock – F2012345678
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
Power reset Yes $0
Connector repair at the heater No $200–$350
Temperature sensor replacement No $250–$400
Heating element replacement by Miele service No $300–$550
Control board or relay repair No $450–$850

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

When to call a technician

Book Miele service as soon as F20 comes back after one power reset, and immediately if the breaker or GFCI trips while the washer heats. You can still run cold programs until the visit if nothing trips.

Frequently asked questions

Can I keep using my Miele with F20?

Cold programs usually still run, since they don't need the heater. Don't use it at all if it trips the breaker or GFCI.

Why did the program take so long before F20 appeared?

Miele washers keep heating until the set temperature is reached. With a dead heater the machine waits until its time limit runs out, then stops with F20.

Is F20 caused by hard water?

Heavy scale can make the element overheat and fail sooner, but the code itself means the element or sensor isn't doing its job. Dosing detergent for your water hardness helps prevent scale.

Is it worth repairing a Miele with F20?

Usually yes. A heater or sensor is a routine repair on a machine built for a long service life, and it costs far less than a new Miele.

Sources