The short answer
A dishwasher that has stopped cleaning properly usually comes down to one thing: the spray arm jets are blocked. Next on the list: the filter stack is fouled. Note the pattern first — whether it is the whole load, one rack, or one kind of item — because that decides which of these it is.
What you observe
- Dishes come out needing to be washed again — Note whether it is the whole load or only part of it.
- The same part of the rack is dirty every time — A repeatable pattern points at a fixed obstruction.
- A gritty film on glasses and the insides of cups — Debris is being carried back rather than carried away.
- One whole half of the load comes out dirty — A stalled arm washes one sector and abandons the rest.
- NEAR MISS — dishes are clean but come out wet — That is a drying and rinse-aid question, not a cleaning one, and it belongs on a different page.
Causes, most likely first on this machine
- The spray arm jets are blocked — First on this machine, because its arms carry small jets that seed and grit lodge in easily, and a blocked jet takes out a whole sector of the load. Owners see the pattern — one part of the rack always dirty — and blame the rack rather than the arm.
- The filter stack is fouled — Ranked here because it is the cheapest cause, the only one an owner can fully correct, and it is right most of the time.
- The spray arms cannot turn freely — Ranked here because it is free to check and because on a tightly-packed machine it happens constantly.
- Scale has built up in the machine — Last, and treated with a machine cleaner rather than a part.
Check in this order, and why
- Take each spray arm off and hold it up to the light — A blocked jet always dirties the same part of the load.
- Lift the filter stack out and look at what is in it — A dishwasher recirculates its water, so the filter decides what ends up back on the dishes.
- Spin each arm by hand with the racks loaded — An arm that catches is an arm that stops in service.
- Look for chalky white deposits in the tub and on the heater — Scale narrows jets and slows heating at the same time.
What an owner can safely check
- Note exactly what comes out dirty and where it sat — Whole load, one rack, or one kind of item — each points somewhere different.
About 10 min
- Remove each spray arm and clear the jets with a cocktail stick — Rinse them through before refitting.
Tools: cocktail stickAbout 20 min
- Remove the filter stack, rinse it under a hot tap and refit it — Twist it fully home; a filter left loose lets debris past.
Tools: warm water, brushAbout 15 min
- Load the machine as usual, then spin each arm by hand — If it catches anywhere, move the item that caught it.
About 10 min
- STOP HERE before removing the heater or the wash pump — Those are behind the tub with live terminals nearby. Service call.
Before you open anything
Safety
Switch the machine off at its spur or breaker before removing any panel, and close the isolating valve before touching a hose. A capacitor can hold a charge after the power is off. Broken glass ends up in the sump on any machine. Wear gloves to clear a filter, and shut the isolating valve before disturbing a hose.
When to call a technician
Call once the filter is clean, the arms turn freely with the racks loaded, the jets are clear and the dose is right, and dishes still come out dirty. At that point it is the wash pump, the heater or the diverter, and all three are behind the tub. Call immediately if the machine trips the breaker, or if there is a burning smell during the wash.
Nearest pages of this class
What this page does not cover
This page is written for the brand and the machine class, not for one family or model line. Where a family- or model-specific page exists for your machine, it is the more specific answer. Deliberately absent: programme charts, place settings, spray-arm and pump part identifiers and wiring colours, which differ between the freestanding and integrated families.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
