When a Miele Dishwasher Smells Bad: Four Smells, Four Causes

A Miele dishwasher smell is diagnosable by what it smells of

That sounds obvious and almost nobody uses it. People describe the problem as "it smells," try a cleaning product, and get a machine that smells of lemon and then of the original thing again a fortnight later.

Four distinct smells turn up on these machines, they have four different causes, and three of them are free to fix. The fourth is the only one that matters today.

Rotten eggs, or straightforwardly like a drain

Sulfurous, worst when the door is first opened, sometimes noticeable in the kitchen without opening it at all.

This is standing water — either in the machine or, more often, in the path between the machine and the sink. The single most common cause is a drain hose that has lost its high loop. The hose is supposed to rise above the level of the sink outlet before it drops, so that nothing can run back. When a machine is pushed into its opening after a repair or a kitchen change, that loop is the thing that gets flattened, and afterwards the sink drains gently into the dishwasher.

Look behind or under the machine if you can reach, or under the sink where the hose connects. If the hose runs flat or downhill the whole way, that is your answer, and it is a bracket rather than a part.

The other version is water that never left the tub. If there is visible water in the base after a cycle, that is a drain problem wearing a smell as a symptom, and it belongs on a different page.

Musty, damp, like a wet dog

The commonest one in this city and the least alarming. Two causes, both environmental, and they compound.

The filters. In the base of the tub, they twist out in two parts and they collect everything the machine washed off. Rinse them under a hot tap with a washing-up brush — not a rinse, a brush — and pay attention to the fine mesh rather than the coarse basket.

A closed machine in a humid room. A dishwasher shut immediately after a cycle in a South Florida kitchen in August is a warm, wet, sealed box. Leave the door on the latch for an hour or two after the cycle finishes and the difference within a week is more than any product will give you.

Fishy

Distinct from musty and it tends to alarm people more. Usually the same two causes as above — filters plus warm standing water — with the particular note that comes from protein residue rather than starch.

The treatment is identical: filters out and properly brushed, hottest program the machine has run empty, door left ajar afterwards. If it comes back within a fortnight, look at the drain path rather than washing the filters again.

Burning, or electrical

Different in kind from the other three, and this is the paragraph to act on rather than read.

Switch the machine off at the breaker and do not run it again. A burning smell — plastic, hot electrics, scorching — is not an odor problem and it does not need airing out. It needs somebody to look at it before the next cycle.

Two things make it more likely on a dishwasher than people assume: something plastic that has fallen onto the heating element in the base, and a heating circuit that is genuinely failing. The first is harmless once removed and looks exactly like the second from the kitchen. Neither is worth a guess.

What actually keeps it away

Three habits, in order of how much they are worth:

• Leave the door on the latch between cycles. Costs nothing, does more than everything else combined in this climate.
• Brush the filters monthly. Not rinse — brush. Ten seconds each.
• Run the hottest program empty once a month, with the machine empty and a detergent tablet in the dispenser. This is the one point where a dishwasher cleaner is genuinely useful, because everything mechanical has already been dealt with.

When it is not the dishwasher at all

If the sink smells when the dishwasher has not run, the plumbing is the source and the appliance is just the nearest opening. A slow-draining sink, a disposal that has not been cleaned, or a trap that has dried out in a rarely-used kitchen will all present as an appliance problem.

Test it by running water into the sink alone for a minute with the dishwasher door shut. If the smell arrives anyway, you are chasing the wrong appliance.

Why this is more common here than almost anywhere

Two things about South Florida make a dishwasher smell that would not in a drier place, and neither of them is a defect.

Ambient humidity. A machine that finishes a cycle and is immediately closed never dries out. In a kitchen where the air itself is carrying water, the interior stays damp between uses indefinitely rather than for a couple of hours.

Water hardness. Scale on the tub walls, the filters and the spray jets gives residue somewhere to hold on to. A machine that has been on the correct hardness setting with salt in it has visibly less to grip, which is why the smell question and the salt question turn out to be related.

Neither means the appliance is wrong for the climate. Both mean the maintenance interval that came in the box was written for somewhere else.

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