The short answer
A DWT dishwasher that will not empty is telling you something is in the way between the sump and the sink waste. That changes the brand-generic order, which opens with the pump: on this platform the sump and its check valve catch debris long before the pump does.
What you observe
- Drain noise that stops early — A pump that changes note and quits part way through usually has debris in the impeller.
- Water backing up from the sink side — A shared waste, a blocked disposer spigot or a sink blockage can push water back into the tub.
- Standing water covering the filter at cycle end — A shallow film over the sump is normal; water above the filter rim is not.
- The machine hums at the drain step but the level does not fall — The pump is being asked to run and cannot move water, which points at a blockage rather than a dead motor.
- NEAR MISS - the tub is dry but the dishes are dirty — That is a wash-flow fault and belongs on the cleaning page instead.
Causes, most likely first on DWT
- Kinked drain hose or a missing high loop — Ranked first on the DWT family: the hose is routed into a cabinet space that was never meant to be inspected, and it kinks where the machine was pushed back. The table above is one platform, so a weakness in the wash path shows on every code in it and not on a single variant. This moves above debris in the filter well and check valve, which leads the brand-generic order, because the platform has run in many trims, and the parts common to every trim accumulate the failures.
- Blocked or jammed drain pump impeller — Second: the impeller is small and sits directly behind the sump, so anything through the filter reaches it immediately.
- Debris in the filter well and check valve — Third: the sump is the low point of the whole machine and the narrowest part of the drain path, which is where glass chips and labels settle.
- Drain pump motor or its control failure — Fourth: last, because a pump that has genuinely failed is a much rarer find than a pump that is simply blocked.
- Blocked disposer spigot or air gap — Last: a new disposer with its knockout plug still fitted is the classic install fault and produces a total no-drain from day one.
Check in this order, and why
- Bail out the standing water and lift the filter stack — You cannot inspect anything under water, and the filter well is the first place debris lands.
- Check the impeller for debris with the power off — Isolate first. A fragment of glass or a label wrapped on the impeller is the common find.
- Check whether the machine ever drained since the last kitchen change — A machine that has never drained since an install points at the spigot plug, not at wear.
- Check the disposer spigot or air gap — Especially worth it if the machine has never drained since a recent kitchen change.
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. Shut the stop tap before disturbing any supply fitting, and leave the door interlock and its wiring exactly as the factory ran them: that interlock is what keeps the machine from spraying with the door open.
When to call a technician
The filter well and the hose run are owner work. Call when the pump itself will not run with a clear path, or when the machine has to come out of the cabinet to reach the hose, because the supply and waste are made up behind it.
Other DWT pages
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
