Denys Mitchell Key Takeaways
- F7 is the built-in water softener reporting a fault, and an empty salt reservoir is by far the most common cause.
- Only coarse dishwasher salt belongs in the reservoir; table salt, rock salt and all-in-one tablets will not regenerate the resin.
- The salt never touches your dishes — it reloads the ion-exchange resin that removes hardness from the incoming water.
- Set the hardness level from your water utility report, not by guesswork, and record it somewhere.
- The machine keeps washing with F7 showing, which is the trap: limescale and glass etching build up quietly for months.
The Bottom Line
Refill the reservoir with coarse dishwasher salt and run one full cycle; F7 normally clears on its own. If it survives a correct refill, the sensor or the brine circuit needs looking at.
Most Asko dishwashers sold in the United States have something the American market is not used to: a built-in ion-exchange water softener, with its own salt reservoir in the floor of the tub. When that system stops working, the machine posts F7. The Asko dishwasher F7 error is rarely a breakdown — it is almost always a maintenance item that nobody knew existed, and left alone it quietly ruins glassware and coats the heating element in scale.
| What you see | What it means | What to do |
|---|---|---|
| F7 with the salt indicator lit | Reservoir is empty or low | Refill with coarse dishwasher salt |
| White chalky film on dishes and cutlery | Softener has been out of action a while | Refill, then run a hot cycle |
| F7 right after a refill | Sensor has not seen the brine yet | Run one full cycle, then recheck |
| Progressive cloudiness on glassware | Limescale etching beginning | Refill now; etching is permanent |
| F7 persists after a correct refill | Sensor, brine circuit, or a cracked reservoir | Book a diagnostic |
| Reservoir refills with water instantly | Possible cracked reservoir body | Stop and have it checked |
Why Your Dishwasher Wants Salt
Hard water carries dissolved calcium and magnesium. Heat them and they come out of solution as limescale — on the heating element, on the spray arms, on the tub walls, and on everything you just washed. Asko's answer is to soften the water before it ever reaches the wash, using a small column of ion-exchange resin.
The resin holds sodium ions and trades them for the calcium and magnesium in the incoming water. After enough cycles the resin is loaded with hardness and has nothing left to trade. That is where the salt comes in: brine drawn from the reservoir flushes through the resin, drives the calcium and magnesium out to the drain, and reloads the resin with sodium. The salt never touches your dishes. It regenerates the filter that does.
The Right Salt, and Why the Wrong One Causes F7
This is the single most common way owners turn a five-minute job into a service call. Dishwasher salt is coarse, granular, and almost pure sodium chloride with nothing added. Nothing else belongs in that reservoir.
- Table salt is wrong. The fine grains pack down and the anti-caking agents clog the brine draw.
- Rock salt is wrong. It carries insoluble minerals that settle in the reservoir and never leave.
- Flavored or iodized salt is wrong. The additives confuse the sensor and coat the resin.
- Combination tablets are not a substitute. The "salt function" in an all-in-one tablet does not regenerate the resin on a machine with a real softener.
Refilling is straightforward once you have the right product. Take out the lower basket, unscrew the cap in the floor of the tub, and fill the reservoir. Water will overflow as you pour, which is normal and not a leak. Wipe up any spilled granules, close the cap firmly, and run a rinse or short wash immediately so the brine circuit flushes and the sensor resets.
Set the Hardness Once, Not Never
The softener has a hardness setting, and it ships on a default that may have nothing to do with your water. Set too low, the resin regenerates rarely, scale creeps back, and glasses go cloudy while the machine reports no fault at all. Set too high, you burn through salt and get a faint salty residue on glassware.
Your water utility publishes an annual report with the hardness figure for your area, and that is a better source than guessing from how the shower feels. Set it once when the machine is installed, and again if you move or if the supply changes. It is a five-minute job that decides how often you will ever see F7 in the first place.
When F7 Is a Real Fault
The code clears on its own after a correct refill and one full cycle. If it does not, the machine is telling you something else. F7 on the Asko dishwasher can also mean the salt level sensor has failed, the brine circuit is blocked by old clumped salt, or the reservoir body has cracked — the last of which shows itself when the reservoir fills with water the moment you add salt.
The machine will keep washing with F7 showing, and that is exactly the trap. Nothing dramatic happens today. What happens instead is that limescale accumulates on the element and the spray arms over months, drying performance drops, and the glassware etching becomes permanent long before anybody treats the code as urgent.
Where It Fits in the Routine
Salt is one of three consumables on these machines, alongside rinse aid and detergent, and the only one most households never learn about. Build it into the same rhythm as the filter.
- Check the salt indicator monthly. Refill when it lights rather than when F7 appears.
- Clean the tub filter at the same time. Our Asko dishwasher filter maintenance guide covers the sump and the flat screen.
- Keep the rinse aid topped up. Softened water still needs rinse aid to sheet off the glass properly.
- Run a hot cycle after a long idle period. Standing water in the brine circuit is what clumps old salt.
- Write down the hardness setting. It saves guessing after a power fault or a board replacement.
The rest of the schedule sits in our Asko dishwasher maintenance guide, and following it makes F7 a code you see once a year rather than a repair.
If It Still Will Not Clear
A softener fault that survives a correct refill needs the machine opened. The sensor, the brine valve, and the reservoir are reached from behind the outer casing, alongside the wiring and the water circuit, which is not a place to experiment.
The site lists this work from $80, which reflects that it is among the lighter repairs on an Asko dishwasher. The final price is confirmed after the on-site diagnosis, and you get a written estimate before any work starts. Our Asko dishwasher repair service covers the softener, the sensor, and the brine circuit. You can book a visit or send us the details and we will tell you whether it is worth one.