The short answer
A dishwasher that has stopped cleaning is usually being starved of water, heat or spray rather than failing mechanically. On a professional built-in cabinet the ranking below starts with the filter and the spray arms because they account for most of these complaints and both are free to deal with.
What you observe
- Gritty residue left on everything — Soil being recirculated, which is the filter.
- Clean on the bottom rack and dirty on the top — The upper spray arm is not getting water or not turning.
- NEAR MISS: dishes clean but still wet — That is a drying complaint, which is about rinse aid and the final rinse temperature rather than about cleaning.
Causes, most likely first on this appliance
- Spray arms that are blocked or not turning — Soil and scale plug the jets, and a tall item in the rack stops the arm turning at all. Ranked first on DCS: these machines are integrated, levelled against a hard counter and plumbed behind a panel, so the installation carries more of the fault load than the machine does, and a heavy professional cabinet installed to tight tolerances has less room for error than its build quality suggests.
- A clogged filter — The filter at the bottom of the tub catches soil so it is not sprayed back onto the dishes. Ranked second: it sits here because on a built-in unit it is a real cause, but reaching it means disturbing the installation.
- Water arriving too cool — A machine fed from a long cold run, or one whose heating element is weak, washes in water that will not shift grease. Ranked third: it ranks below the causes above because those are visible from the front and this one is not.
- A weak circulation pump — The cause left once the filter, arms, load, detergent and temperature are all clean. Ranked last: it is last because these components are built to a long service life, and because confirming one needs instruments and a service manual that are not owner tools.
Check in this order, and why
- Spin each arm by hand and check the jets — An arm that catches, or holes you can see are blocked, is the cause and it is clearable at the sink.
- Take the filter out and look at it — A filter with a soil mat across it explains gritty dishes on its own, and no other check is worth doing before this one.
- Run the kitchen tap hot before starting the machine — A cycle that cleans better after the tap has been run hot tells you the supply temperature was the issue.
What an owner can safely check
- Remove the spray arms, clear every jet and refit them — Unclip each arm, push a cocktail stick through any blocked jet, rinse them out and refit.
Tools: cocktail stickAbout 20 min
- Remove, rinse and refit the filter assembly — Twist the filter out, rinse it under a tap with a brush, clear the sump beneath it and refit it until it locks.
Tools: soft brushAbout 15 min
- STOP HERE if the next step needs a meter on live terminals or a panel off — That is where an owner check ends and a service call begins.
Before you open anything
Safety
Switch the machine off at its breaker before reaching into the sump or removing anything below the lower rack, and keep it off while your hands are inside. Expect broken glass and sharp soil in the filter and the sump: use a cloth rather than bare fingers. Do not mix cleaning products in the tub, and in particular never combine bleach with anything acidic.
When to call a technician
Call once the filter, the spray arms, the load, the detergent and the supply temperature have all been addressed and the machine still washes poorly, because what is left is the pump, the heater or the inlet valve. Call sooner if the machine no longer sounds like it is spraying at all, or if the tub is not draining between phases.
Nearest pages of this class
What this page does not cover
This page covers DCS as a family, not one model line. Where a page exists for the line named on your plate it is linked below and it is the more precise answer. Not here: the filter assembly and spray arm part numbers, and the cycle temperatures for your specific machine, which vary by model.
Links: - [DCS by Fisher & Paykel dishwasher not cleaning: causes ranked and what to fix first (the later DCS by Fisher & Paykel platform)](/blog/dcs-by-fisher-paykel-dishwasher-cleaning-performance-2)
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
