Won't drain
A dishwasher that won't drain is failing somewhere in a short chain from the sump to the house drain: the drain pump pushes water out of the tub, the drain hose carries it up and over a loop or through an air gap, and the water enters the house drain through either a dedicated standpipe or the inlet on a garbage disposal. Each point in that chain can clog — and the single most common cause isn't the pump. It's food debris accumulated in the sump filter at the bottom of the tub. On brand-new installations, a specific failure mode dominates: the garbage disposal inlet has a factory 'knockout plug' that the installer has to remove before connecting the dishwasher. If that plug was forgotten, no water can pass regardless of how healthy the dishwasher's pump is. Check the sump filter first on an existing install, and check the disposal knockout on a new install, before assuming a component has failed.
Safety
Critical- Kill the breaker before opening any panel: Dishwashers are typically hardwired to a dedicated 120V circuit rather than plugged into an outlet, so there's no plug to pull. Always turn off the dishwasher's breaker at the panel before removing the kick plate, accessing the drain pump, or working inside the tub. Verify power is off with a non-contact voltage tester before reaching in.
- Sharp debris in the sump and filter: Broken glass, toothpicks, fruit stickers with backing staples, and small bones or shells collect in the sump and filter. Always inspect visually before reaching in, and pull debris out with tweezers or a disposable tool — not bare fingers. A small shard of glass in the sump is easy to miss and easy to cut skin on.
- Standing dishwasher water is not clean: Water trapped by a failed drain cycle carries detergent residue, food particles, and the slippery proteins and fats from whatever was rinsed off dishes. It can irritate skin and eyes, and it smells bad if left sitting for more than a day. Wear gloves when bailing water from the tub or cleaning the sump.
- Don't force additional cycles with water in the tub: Running another cycle on top of standing water risks overflow onto the floor and through the door gasket. Cancel the current cycle, bail water out of the tub manually with a cup or sponge, and diagnose the drain path before starting any new cycle. The door gasket is not watertight against significant volume.
How to approach this
Start inside the tub. Pull the lower rack out and locate the sump filter at the bottom — a cylindrical or flat-disk assembly in the center-rear on most models. On manual-clean filters, twist counterclockwise to remove and rinse under running water; on self-cleaning filter models, check the sump area around the drain for food debris anyway, since even self-cleaning filters miss larger items like broken glass or fruit stickers. Next, if the dishwasher connects to a garbage disposal, run the disposal briefly with water to clear any backed-up water, then confirm the disposal knockout plug was actually removed at installation — shine a flashlight into the disposal inlet (dishwasher connection port) and look for an obstruction. If there's an air gap on the countertop, twist off the cap and check for food debris clogging the device. Finally, pull the lower kick plate and inspect the drain hose for kinks, and if nothing else has been found, test the drain pump by listening for its motor during a drain cycle — a hum without water movement points at a jammed impeller, silence points at a failed motor or missing control signal.
Repair tips for this model
From OEM manual analysis for the DDW24T998US
From the service manual
Good to know
5 technician insights for this model
Post-service verification checklist is critical
After finishing any service: (1) Check door lock switch operation — must lock during run and stop when unlocked, (2) Use only authentic Samsung replacement parts, (3) Check all wires are not loose or tight, correctly connected, bound with tape, and properly clamped, (4) Check all screws and nuts fastened with specified torque, (5) Remove all foreign material from inside tub and sump, (6) Run normal cycle and check for water leakage from hose connectors, door, case sump, motors, heater, thermistor, sensors, and supply/drain hoses, (7) Check power cable and outlet, (8) Verify dishwasher is level, (9) Check installation is on flat/stable surface.
Waterwall linear wash is unique to this series — different from standard rotating spray
These models feature a Waterwall linear wash system in addition to standard rotating nozzle spray. The Waterwall creates a high-pressure, consistent wall of water that cleans hard to reach places. This means no pre-rinsing is needed. Available on full or half cycle. The main pump runs at 96W during Waterwall operation versus higher wattage for standard spray.
Circulation pump hose clamp is single-use — order replacement before service
When removing the circulation pump, the hose clamp cannot be reused after removal. You must have a new clamp ready as a service part before starting the disassembly. Order the replacement clamp in advance. This applies to the clamp connecting the pump hose to the sump.
Circulation pump error is ignored during low water level sensing
When the dishwasher detects a low water level condition, the 3C circulation pump check code is intentionally ignored. This prevents false pump errors when the pump is running dry due to insufficient water. If you see 3C errors, always check water supply and water level first before diagnosing the pump.
Common causes
Ordered by how frequently each component is involved, based on OEM manual analysis.
Clogged sump filter or sump area
Most commonFood debris that doesn't fully dissolve in the wash collects in the sump at the bottom of the tub — especially fruit stickers, rice grains, popcorn kernels, and fat-stuck residue. On models with manual-clean filters, users often don't know to rinse them monthly. On self-cleaning filter models, larger debris like broken glass still accumulates in the sump around the filter housing. Pull the bottom rack and inspect with the tub empty.
Garbage disposal knockout plug still installed (new installs)
CommonWhen a dishwasher connects to a garbage disposal, the disposal's dishwasher inlet port ships from the factory with a 'knockout plug' that must be driven out with a hammer and punch during installation. If an installer skipped this step, no water can pass from the dishwasher into the disposal — the dishwasher fills and then can't drain. This is the dominant failure mode on brand-new dishwasher installs and appears within the first few cycles.
Clogged air gap (where installed)
CommonAn air gap is a small cylindrical device on the countertop or sink deck, required in California and some other jurisdictions and common throughout the western US. It prevents contaminated sink water from backflowing into the dishwasher. Food debris and detergent residue clog the air gap internals over years, slowing or stopping drainage. Twist off the decorative cap and clean the interior with a brush and vinegar — a frequently overlooked maintenance step.
Kinked or obstructed drain hose
CommonThe drain hose runs from the dishwasher's drain pump outlet up and over a high loop (or to the air gap), then back down to the disposal or standpipe. Kinks can form when the dishwasher was pushed back into the cabinet during install, and the interior of the hose builds up grease and food residue over years. Disconnect both ends and run water through it to confirm clear flow.
Failed or jammed drain pump
CommonThe drain pump mounts below the sump and is driven by either a dedicated motor or a shared motor with the circulation pump. Foreign objects (broken glass shards, fruit stickers, small bones, pits) can jam the impeller — a hum with no water movement is the classic signature. True motor failure (open windings, bad bearings) produces silence on drain command. Access the pump by removing the kick plate and lower service panel. Replacement pumps run $50-150.
Verified Components
Parts
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About this content. Common causes and FAQs are generated from OEM manual analysis and verified parts data. This is general guidance - your specific model may have different components or access points. Always verify with your model's documentation before ordering parts.