The short version
When the WQP dishwasher stops cleaning properly the machine has almost always lost spray coverage. Blocked arm jets, a filter the owner did not know existed and items blocking the upper arm explain the great majority of these calls before any part is suspected.
The observable signs on this platform
- One rack clean, the other not — A spray-coverage split. Either that arm is not turning, its jets are blocked, or something in the load is fouling it.
- A white chalky film on glassware — Hard water and detergent chemistry rather than a mechanical fault. It responds to rinse aid and dosing, not to parts.
- Baked-on residue that survives the cycle — Points at wash temperature or a cycle too short for the soil level, and on some builds at a heater that is no longer contributing.
- NEAR MISS — the machine is also not draining — Standing water at the end of a cycle is a drainage fault, and dirty dishes are only its side effect.
Causes, most likely first on the WQP family
- Filter loaded or seated incorrectly — First on this family, and first because owners are frequently unaware the filter needs periodic cleaning at all. Once it is loaded the machine washes with suspended debris and redeposits it, which produces exactly the gritty finish people describe.
- Spray arm jets blocked, or an arm not turning — Second. Hard-water scale and food fragments close the small jets first, so coverage degrades gradually and the owner blames the detergent.
- Loading pattern blocking coverage — Third, and free to rule out. Tall items, oversized trays and pan handles reaching down through the upper rack all stop an arm dead.
- Water temperature or detergent dosing wrong for the water — Fourth. Detergent that never dissolves cannot clean, and hard water binds it before it works. This produces film and poor results without any part having failed.
The order to work in, and the reason for it
- 1. Pull and clean the filter assembly — Remove it, rinse it, check it seats fully on refitting.
- 2. Spin both spray arms by hand and hold each jet up to the light — Any arm that catches, and any jet you cannot see through, is your coverage fault.
- 3. Load the machine as the household actually loads it, then spin the arms again — This is the step that catches the tall item nobody thought about, and it is the difference between a real diagnosis and a parts guess.
Safety first
Safety
Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. Opening the door mid-cycle releases steam and hot water, so open it a crack, stand aside and let the machine stop before looking in.
Models in the WQP family — The model numbers this page covers.
Reference| Model number | Family key |
|---|---|
| WQP12-77E1B-US | bertazzoni:dishwasher:wqp |
| WQP8-7740-US | bertazzoni:dishwasher:wqp |
When to call a technician
Call when the filter is clean, both arms turn freely with clear jets, the load is not obstructing anything and the results are still poor across both racks, because that pattern points at wash pressure and that means the pump or the diverter. Call as well if the machine sounds different during the wash — a pump that has lost prime or picked up debris changes its note. Filter cleaning, jet clearing and loading corrections are all owner work and resolve most of these calls without a part.
Other problems covered for the WQP family
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
