Answer first
On a Wizard dishwasher, leaving dishes dirty usually comes down to a choked filter and coarse screen, with spray arms blocked, or their jets scaled shut next. Change one thing at a time and run the same soil again, because that is the only way to tell chemistry from mechanics here.
What you actually observe
- Food left on the load after a full cycle — Usually in the same places on the rack, cycle after cycle.
- A gritty film on glasses and the inside of the tub — Redeposited soil rather than soil that was never removed.
- NEAR MISS — there is standing water in the bottom after the cycle — That is a drainage fault, and soil in that water is why the load is dirty; start with the drainage page.
Causes, most likely first on this platform
- A choked filter and coarse screen — First on a machine of this generation. Older machines rely on a coarse screen and a chopper rather than a fine filter, and once that screen glazes over the same water goes round the load for the whole cycle.
- Spray arms blocked, or their jets scaled shut — An arm that cannot turn, or that turns with half its holes closed, leaves whole sections of the rack untouched. Second: decades of hard water scale the arm jets shut one hole at a time, so the wash pattern narrows long before anything breaks.
- A worn wash pump or impeller — Third. A pump with this many cycles behind it has lost pressure, and the top rack is always where that shows first.
- Detergent type, dose and water hardness — Fourth, and still worth ruling out first because it costs nothing: modern detergents are formulated for machines that hold water hotter and longer than this one does.
Check in this order, and why that order
- Take the bottom filter out and look at it — Soil that cannot leave the sump is sprayed back over the load for the rest of the cycle. It goes first: top-ranked above, and free to rule out.
- Take each arm off and hold it up to the light — Jets that are scaled shut narrow the wash pattern long before the pump gives up. Second: the next cause in the ranking, and this check separates it from the first.
- Listen to the machine through the main wash — A wash that sounds weak and an upper rack that stays dirty together point at pressure. Third, once both checks above come back clean.
What an owner can safely check
- Remove and rinse the filter assembly and the coarse screen under a hot tap — A soft brush gets the mesh clean; put it back locked into place, or the pump will pick up debris.
Tools: soft brushAbout 15 min
- Unclip both spray arms and clear every jet, then check each arm spins freely — A cocktail stick clears a scaled hole without enlarging it.
Tools: cocktail stickAbout 20 min
- Listen to the machine through the main wash — A wash that sounds weak and an upper rack that stays dirty together point at pressure. Note what you find.
About 5 min
- STOP HERE if the next step needs the machine unplugged and a panel removed — Anything behind the outer panel of a machine holding water and mains wiring is a service call.
Before you take anything off
Safety
Unplug the machine or switch off its breaker before removing any panel; a capacitor can hold a charge after the power is off, and this machine holds water and mains wiring in one cabinet. Never defeat the door latch switch, and never reach into a sump or a drain pump that is still plugged in: broken glass goes through a rubber glove.
Where an owner check ends
Call once the filter is clean, the arms spin freely, the detergent is right and the results have not changed, because what is left is pressure, heat or a diverter and all three are behind the tub. There is no hazard in waiting, only dishes. On a machine of this age, ask what the repair costs against what the machine is worth before agreeing to it, and ask whether the part can still be sourced.
Where to go next in this class
What this page does not cover
This page is written for the Wizard dishwasher as a class, not for one family or model line. Where a family- or model-specific page exists for your unit it is linked here, and it is the more specific answer. Not here: part numbers, wiring colours, torque figures, panel sequences and component ratings, which differ by family.
Links: - [Wizard dishwasher leaking onto the floor: where it starts](/blog/wizard-dishwasher-water-leak) - [Wizard dishwasher not draining: water left in the bottom](/blog/wizard-dishwasher-drainage-failure) - [Willz dishwasher leaving dishes dirty: what to check first](/blog/willz-dishwasher-cleaning-performance)
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
