The short answer
A Home dishwasher leaving dishes dirty is usually short of spray coverage or water temperature rather than suffering a failed pump. The first thing to check: filter and sump loaded with debris. The filter and the arms take a quarter of an hour and settle most of these complaints.
What you observe
- A gritty film on glasses and the inside of cups — Dirty wash water, which is the filter.
- One rack clean and the other not — Spray coverage: an arm blocked or not turning.
- NEAR MISS — there is standing water in the bottom at the end — Water left in the tub is a drainage fault, and it spoils cleaning as a side effect. Read the drainage page for this brand.
Causes, most likely first on a Home dishwasher
- Filter and sump loaded with debris — The filter keeps food out of the recirculating water. Once it loads up, the machine washes with dirty water and redeposits soil onto everything, which shows first as a gritty film on glasses. A badge-engineered machine uses standard consumables, and standard consumables are what fail first. This is the cheapest cause on the list and the most common one.
- Spray arm holes blocked, or arms fouled by tall items — The arms have to spin freely and reach every rack. Holes blocked by seeds or scale narrow the pattern, and a tall item that stops an arm turning leaves a whole section of the load untouched. A badge-engineered machine uses standard consumables, and standard consumables are what fail first. This is the cheapest cause on the list and the most common one.
- Loading blocking the spray, or items nested together — Water cannot clean a surface it never reaches. Bowls nested, large plates shielding the rack behind them, and pans laid flat all leave a load that comes out half clean with nothing wrong with the machine. Nothing on this machine is clever enough to compensate for how it is loaded, so the loading cause ranks high rather than being an afterthought.
Check in this order, and why
- Lift out the filter at the bottom of the tub and look at it — First because it is free, quick, and the most common cause by a distance. It is first because it is the highest-ranked cause here.
- Spin each spray arm by hand and check the holes are clear — Second: free, and it explains a load that is clean in one place and dirty in another. Second: the next most likely, and free to rule out.
- Look at how the load was arranged when it failed — Third, free, and a real cause rather than a polite excuse. Third, and only once the two above are clean.
What an owner can safely check
- Remove the filter, rinse it under a hot tap and clear the sump — Check the sump underneath for glass, labels and seeds, and refit the filter so it locks home.
Tools: brush, glovesAbout 20 min
- Run a hot cycle empty with a dishwasher cleaner or white vinegar in the tub — This clears grease and scale from the arms and the sump, and it is the honest baseline before judging anything else.
Tools: white vinegarAbout 90 min
- STOP HERE if the next step needs a panel off or a meter on live terminals — Everything past this point belongs to a technician.
Before you open anything
Safety
Switch the machine off at the breaker before removing any panel or reaching behind it. A capacitor can hold a charge after the power is off. Wear gloves when clearing a filter or a sump: broken glass collects there and is not always visible. Never mix cleaning products in the tub, and never use bleach with a detergent that contains chlorine.
When to call a technician
Call when the filter, the arms, the loading, the temperature and the detergent have all been checked and the results are still poor, or when the wash sounds noticeably weaker than it used to. Call immediately if the machine smells of burning during a cycle. If the dishes come out cold at the end of a cycle, mention it when you book: that points at the heater rather than at anything the owner can reach.
Nearest pages of this class
What this page does not cover
This page covers Home dishwashers as a class, not one family or model line. Where a family- or model-specific page exists for your unit, that page is the more specific answer and the one to read first. Deliberately not here: wiring colours, torque figures, part numbers and service-manual sequences, which differ by family.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
