Miele [F66] fault codewhat it means and how to fix it

Search for this code anywhere else and you will mostly be told it is an airflow fault requiring an engineer. Miele’s own page says something quite different, and it opens with advice rather than diagnosis: "F66 is displayed in many cases because the fluff filters or the plinth filter have not been cleaned or have been cleaned insufficiently. Clean the fluff filters after every drying programme. Clean the plinth filter immediately when Filter lights up or a prompt appears in the display. This allows you to reduce the frequency of fault F66 or even prevent this fault."

Then they list eight causes, and only the last one is a technical fault. The other seven are the fluff filters being dirty, the plinth filter in front of the heat exchanger being dirty, the machine being overloaded, the ventilation grille under the door being obstructed, insufficient ventilation in the room — Miele note this can make the room temperature rise sharply — the plinth filter being encrusted, and the plinth filter being damaged or out of shape. That last one deserves emphasis. A plinth filter that has distorted or split no longer seals against the air path — Miele’s words are that it "will no longer fit tightly" and "fluff will get into the heat exchanger unfiltered" — and no amount of cleaning fixes it. It is a consumable part, between about twenty and forty pounds on Miele’s own shop depending on the series.

If your machine is a few years old and this code keeps returning after thorough cleaning, look at the shape of the filter rather than booking a visit. One more thing Miele say that is easy to miss: a plinth filter refitted wet causes a fault message of its own, so a code that appears straight after cleaning may simply mean the filter went back in before it had dried.

1. 1

   Take the washing out and spread it before working on the machine, rather than leaving it heaped in the drum or a basket.

2. 2

   Clean the fluff filters the way Miele describe: open the door, pull the upper fluff filter forwards to remove it, then turn the yellow rotary control on the lower fluff filter in the direction of the arrow until it clicks and pull that filter forwards too. Clear the fluff from every filter surface and the perforated laundry deflector, and use a vacuum cleaner with a crevice nozzle on the upper air flow openings. Wipe the smooth plastic with a damp cloth, rinse the filter surfaces under warm running water, shake and dry them carefully, then push the lower filter in and lock it with the rotary control and push the upper filter all the way in. Miele want this done after every programme, so if yours are not on that schedule this is likely the whole answer.

   Miele: "Wet fluff filters could cause operational faults while drying." Dry them before they go back.
3. 3

   Press the round, indented area on the heat exchanger access panel at the bottom of the machine and it springs open. Pull the plinth filter out by its handle (the right-hand guide pin comes out with it — it stops the panel closing without a filter in place), pull the handle out of the filter, and clean the filter carefully and thoroughly under running water, squeezing it several times as you rinse. Miele suggest doing this in a bowl or bucket and pouring the water through a coffee filter afterwards so the fluff goes in the household waste rather than the drain.

4. 4

   Squeeze the water out until the filter is no longer dripping, and leave it to air-dry if you can — Miele suggest pressing it between two hand towels on a flat surface to speed this up. Do not refit it dripping wet. Miele are explicit that a programme interrupted by a fault message after the filter has been refitted means the filter was still too wet.

5. 5

   While the filter is out, look at the heat exchanger behind it. If fluff has collected on the fins, remove it with a vacuum cleaner fitted with a dusting brush, passing the brush over the fins lightly without applying any pressure.

   Miele: "Risk of injury from sharp cooling fins. You could cut yourself. Do not touch the cooling fins with your hands." Bent fins stop the machine drying, so no hard nozzles and no pressure.
6. 6

   Hold the plinth filter up and look at it. White encrustation on the edges and front is detergent residue: Miele’s remedy is to wash the filter on its own in the washing machine without detergent at no more than 40 °C and a spin of no more than 600 rpm. If it is torn or has lost its shape, replace it — Miele list damaged and out of shape as a cause in its own right and sell the filter through their online shop.

7. 7

   Wipe any fluff off the handle with a damp cloth, fit the filter back on the handle the correct way round, push it in completely so the guide pin goes in with it, wipe the seal area without damaging the rubber seal, and close the access panel.

8. 8

   Check the ventilation grille under the door is clear, and that the machine is not in a small sealed room. Miele note poor ventilation can raise the room temperature sharply, which causes this code with nothing broken, and on a condenser dryer they say to open a door or window while drying.

9. 9

   Reduce the load size and run a programme. If F66 returns with clean, dry filters, a sound plinth filter, a clear grille and a ventilated room, you have reached Miele’s eighth cause and it is time to call.