The short answer
Dishes coming out dirty on a DWT machine is nearly always water not reaching them rather than a machine that has lost its power. A slim built-in tub shadows its spray arm sooner than a wide one, so loading leads the ranking here.
What you observe on these models
- Gritty deposits on the items at the back of the lower rack — The arm is being stopped or shadowed before it reaches them.
- Cutlery comes out worse than plates — Nesting in the basket, which is a loading fault rather than a machine one.
- Results are fine on a long cycle and poor on a short one — That is the programme, not the machine.
- Baked-on food surviving the wash but coming off with a finger — The water reached it and the detergent did not work, which points at temperature or detergent age.
- NEAR MISS — dishes are clean but wet — That is a drying and rinse-aid question, not a wash question.
Causes, most likely first on the DWT family
- Loading, and the spray arm it shadows — First on this platform: a tall item in the wrong slot stops the lower arm turning, and a machine whose arm cannot turn washes one quarter of the load properly. Spin the arm by hand with the racks loaded: if it stops anywhere, you have found the fault.
- Blocked jets in the spray arms — Second: the holes are small, and grit, label paper and seed husks block them from the inside. The pattern is a load that is clean at the front and untouched at the back.
- The cycle being used — Third: short and eco cycles run cooler and shorter by design. A machine that cleans on a long cycle and not on a quick one is telling you about the programme rather than about itself.
- Items nesting against each other — Fourth: two bowls stacked, or cutlery packed in one direction, shield each other from the spray completely. The result looks like a machine fault and is a loading habit.
- Detergent that has gone off — Last: tablets and powder absorb moisture and lose their enzymes. A box open in a damp cupboard for a year is a genuine cause of poor results.
Check in this order, and why that order
- Load the machine, then spin both spray arms by hand — If an arm stops against anything, that is your fault and you have found it in ten seconds.
- Take the arms off and look through the jets at a light — Blocked holes are obvious from the inside and impossible to see from the outside.
- Spin the spray arm by hand with the racks loaded — Portables are loaded low where it is hard to see what is shadowing it.
- Take two items out and run the same cycle again — On a tub this size that is a real test, not a guess, and it answers the question in one cycle.
- Halve the detergent dose for a cycle — A full-size tablet is too much for this volume of water.
Before you open anything
Safety
Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. Treat that as the first step of every check below that involves a panel, a grille or a cover.
Models in the DWT family — The numbers this page covers.
Reference| Model number | Family key |
|---|---|
| DWT18V3S | avanti:dishwasher:dwt |
When to call a technician
Spray arms, filters, loading, detergent and water temperature are all owner work on a built-in dishwasher and between them they account for most poor wash results. On these models the line falls at the drain pump, the door switch and the control board. Call without working through anything at all for water arriving from under the machine with every visible joint dry.
Nearest pages of this class
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
