Miele F86 fault codewhat it means and how to fix it
The salt reservoir flap in the door is not closed. Ten seconds to fix, and worth doing properly because loose salt corrodes the tub.
Before you start
What F86 means
F86 means the salt reservoir flap in the door is not closed, which is about as benign as a fault code gets — it is the machine noticing you did not screw the cap back down after topping up the softener salt. It is worth knowing about rather than dismissing, though, because the consequence of ignoring it is not nothing. The salt reservoir holds a strong brine solution, and a machine running with the flap open will wash that brine around the tub. Salt water and stainless steel are a poor combination over time, which is why manufacturers across the industry tell you to run a programme immediately after filling the reservoir: it dilutes and flushes away whatever spilled during the refill. A machine running with the flap open does the opposite. While you are down there it is worth understanding what the reservoir is for. Every Miele dishwasher has a built-in water softener, and it needs regenerating with coarse dishwasher salt — not table salt, which contains additives that will damage the softener. Hard water is what fills your glasses with white film and what eventually scales up the heating element, and the salt is the thing standing between you and both.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Flap not screwed down after refilling | The whole of the code, almost every time. It needs to be turned firmly rather than dropped into place. | Common |
| Salt granules on the thread | Spilled salt under the cap stops it seating flush. Brush the thread clean before refitting. | Common |
| Cap or seal damaged | A cracked cap or perished seal that will no longer close properly. A cheap part rather than a repair. | Occasional |
What to try yourself
Take out the bottom basket and find the salt reservoir cap in the floor of the tub. Check whether it is properly screwed down.
Unscrew it, brush any loose salt off the thread and the seal, and screw it back down firmly.
Run a programme straight away rather than leaving it. This flushes out any salt spilled during the refill, which is what protects the tub from corrosion.
Do not leave a machine standing with salt spilled in the tub. Brine on stainless steel causes corrosion over time.While you are there, check you are using coarse dishwasher salt rather than table salt. Table salt contains additives that damage the softener, and it is a genuinely common mistake.
Get a qualified appliance engineer to look at your Miele F86
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What it costs to fix
Typical repair cost
£0–£40
Time on site
10 minutes
Free in almost every case. A replacement salt reservoir cap, if the original is cracked, is typically £15 to £40.
Typical UK prices including parts and labour, updated August 2026. Your quote may differ.
What other owners found
Nobody has shared what worked for them on this code yet. If you have had it, you would be the first — and it genuinely helps the next person.
Related Miele fault codes
- E12Get it checkedThe heating element has furred up with limescale. Descaling fixes today; setting the water softener correctly stops it coming back.Related: water softener and salt
- F11Get it checkedWater left standing in the cabinet because the machine cannot drain. Miele treat this as an owner job and walk you through the drain pump.Related: same brand
- F12Get it checkedThe water inlet is blocked or restricted. Miele use the same wording for F13, F15 and F173, and warn that the hose connection houses an electrical valve.Related: same brand
- F70Stop — call an engineerThe Waterproof System has activated. Miele give the clearest emergency instruction of any dishwasher manufacturer — close the stopcock, switch off, unplug, call.Related: same brand
- F69Get it checkedThe circulation pump is blocked. Miele distinguish this from a pump fault, and a blockage is yours to clear.Related: same brand
- F52Usually simple to fixA sensor has detected too much foam and stopped the programme. Nothing is broken — the machine is protecting itself from suds.Related: same brand
Common questions about Miele F86
Can I use table salt?
No. Dishwasher salt is coarse and pure; table salt, sea salt and cooking salt contain anti-caking agents and other additives that clog and damage the softener unit. A box of the right stuff costs a couple of pounds and protects a component that costs a great deal more.
I use all-in-one tablets. Do I still need salt?
In most of England, yes. All-in-one tablets contain a salt substitute that works up to moderate hardness, but a lot of the country is harder than that. If your glasses are filming up or you are seeing scale inside the machine, the tablets are not keeping up on their own.
Why does the machine care whether the flap is shut?
Because an open reservoir washes concentrated brine round the tub for the whole cycle, and salt water attacks stainless steel over time. It is a small fault the machine reports for a real reason.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer support portal