Resist the urge to run a cleaning cycle and hope for the best. Checking drainage first tells you whether this is a quick cleaning job or something bigger, and running extra cycles on a machine that isn't draining properly just adds more contaminated water to the mix.

1. Turn off the dishwasher's breaker before reaching into the sump or removing the filter, and put on heavy-duty rubber gloves. Broken glass, bone fragments, and pop-tabs turn up in the filter pit more often than you'd expect (Axis Repair).
2. Look at the water sitting around the sump. About a cup of clean water is normal; it keeps the rubber seals from drying out and cracking. Water covering the top of the filter, or water that smells foul, points to a drainage problem, so skip ahead to the drainage section below (Axis Repair).
3. If the water level looks normal, start with the filter. Frigidaire's own troubleshooting asks the same first question, whether the filter and glass trap have been cleaned, before pointing to anything else (Frigidaire).

Cause 1: dirty filter

A clogged bottom filter is one of the most consistently identified causes in the appliance guidance reviewed here. It traps rotting food debris and sits at the bottom of the tub (Axis Repair; Frigidaire). Twist or lift the filter assembly out (the release mechanism varies by model, so check the manual before forcing anything), rinse it under the tap, and clear any debris caked around the sump edge (Electrolux).

If dishes come out smelling like wet dog or raw eggs specifically, that's a known combination: sulfur compounds from egg residue bind to bacteria already living in a dirty filter. Pre-rinsing egg yolk off plates and cleaning the filter clears it up (Axis Repair).

Cause 2: clogged spray arms

Rice, seeds, and other small debris lodge in the spray holes, which restricts water coverage and leaves residue behind to rot (Axis Repair). Pull the arms out and clear the holes using the method specified in your manual, then reseat them fully. It's a standard maintenance step on Electrolux machines (Electrolux).

Run one cycle once both are clean and the water level checked out normal earlier. Smell gone, you're done. Smell still there, move to the buildup causes below rather than the drainage section; a clean filter with a persistent odor may point to grease, scale, gasket buildup, or a drainage problem that needs a separate check.

One habit keeps most of this from coming back: clean the filter and glass trap every two to three months, whether or not there's an active smell (Frigidaire).

Cause 3: grease, hard-water scale, and biofilm

Dishwashers accumulate grease and mineral scale on the tub walls over time, sometimes visible as a faint slime, even when the filter is spotless. It collects mostly in spots the wash spray doesn't reach well, like behind the baskets and runners (Electrolux; Axis Repair).

Wipe the reachable surfaces weekly, and run a dishwasher-specific cleaning product at least once every two months (Electrolux). Frigidaire's alternative is an empty cycle with a cup of white vinegar and no detergent, or its sanitize setting (Frigidaire). Commercial tablets, which use citric acid and sodium percarbonate to break down scale, run roughly $5 to $10 for a multi-pack and work well as a monthly preventive measure according to the repair company that sells the service, though they won't clear a physically clogged filter (Axis Repair).

If the smell shows up mainly during the drying cycle, treat it as a buildup problem and deep-clean the tub interior (Axis Repair). If that smell ever shifts from something food-like to burning plastic, stop and skip to the electrical warning near the end of this guide.

Cause 4: dirty or deteriorating door gasket

A moldy or grimy door gasket is a separate problem from tub buildup, sometimes visible as black or pink slime along the seal and hinges (Axis Repair). Wipe the seal and door edge by hand for routine grime (Electrolux). If wiping doesn't clear it after a couple of tries, the gasket itself may need replacing rather than repeated cleaning; check the manual for the part number or have a technician swap it in.

Never mix bleach with vinegar or ammonia-based cleaners, since the combination produces toxic gas. Never use bleach in a dishwasher with a stainless-steel interior, since it pits and permanently damages the metal. For a stainless-steel tub, avoid bleach and follow the appliance manual; if it permits household cleaners, use vinegar or baking soda as directed, not as an improvised mixture (Axis Repair).

If the filter and spray arms are clean but the smell keeps coming back, especially something sewage-like between cycles, drainage is next. This is also where the fix stops being a simple wipe-down and starts requiring a judgment call about who should handle the next step.

Cause 5: kinked or clogged drain hose

A kinked or partially clogged drain hose holds stagnant water and produces a stale, sometimes sewage-like smell even after the filter is spotless (Axis Repair). Check the hose's visible routing under the sink for obvious kinks; if you find one, clearing it is a DIY job.

Cause 6: blocked air gap or missing high loop

If the hose looks fine, check the sink air gap or high loop next. An air gap creates a physical break of air between the dishwasher hose and the disposal hose, which makes backflow physically impossible as long as it's clear (Bryco Plumbing). A high loop instead relies on gravity and a small internal check valve, which can seize in hard-water areas; the Uniform Plumbing Code generally calls for an air gap, while some jurisdictions following the International Residential Code allow a high loop instead (Bryco Plumbing).

Water surfacing at the top of a visible air gap almost always means the disposal-side hose is blocked, not the dishwasher itself, so clear that blockage rather than taking the appliance apart (Bryco Plumbing). Most dishwashers now ship with an internal loop built into the side of the unit, but a separate high loop or air gap may also be required, depending on the appliance instructions and local code (LCAR Online). A home inspector who flags this as a routine defect notes that manufacturers require one or the other regardless of what's built into the unit; check the installation manual or ask a plumber rather than assuming a visual check settles the question (LCAR Online).

Cause 7: failed drain pump

If the hose and air gap both check out clean but water still won't drain, or standing water keeps coming back after cycles, that points toward the drain pump. Diagnosing and replacing one isn't really a DIY repair, so this is where an appliance technician earns their visit. Pump-related repairs typically run $200 to $350 for parts and labor depending on the brand, while a simpler service call for clearing a hose or air gap runs closer to $125 to $180 (Axis Repair).

Cause 8: improper drain installation

If drainage checks out completely, clear hose, properly installed loop or air gap, but a sewage smell persists between cycles anyway, the dishwasher's drain line may be tied in downstream of the sink's own trap. That can allow sewer gas to enter through the dishwasher, and it's a defect a home inspector calls out routinely. It needs a licensed plumber rather than a cleaning product, since the applicable code, UPC or IRC depending on where you live, governs the fix (LCAR Online; Bryco Plumbing).

A burning-plastic, fishy-electrical, or ozone smell isn't an odor-buildup problem at all. It signals melting wires or a failing control board (Axis Repair).

Turn off the breaker immediately and call a professional. Don't run another cycle to try to clean it out first; that's the move that turns a manageable repair into a much bigger one (Axis Repair). This is also a different call than the plumbing and pump issues above. You want an appliance repair technician or an electrician, not a plumber.

Scrape food off dishes before loading, and use the prewash cycle if the machine has one; both cut down on what actually reaches the filter (Electrolux).

Wipe the gasket, door edge, and areas behind the baskets weekly. Those spots sit outside the wash spray's reach, so the cycle itself never really cleans them (Electrolux).

Keep the drain, drain spigot, and hose clear and free-draining. A restricted drain causes both poor cleaning and bad odors, so it's worth checking occasionally even when nothing smells wrong yet (Electrolux).

Clean the filter every two to three months and the whole unit every three months, whether or not there's a smell to chase (Frigidaire).

The nine causes above split cleanly by who should fix them. The filter, spray arms, tub buildup, and gasket grime are jobs you can do yourself with basic tools. A pump that won't drain despite a clear hose and air gap calls for an appliance technician. A drain installed against code calls for a licensed plumber who knows the requirements in your area. Any burning-plastic or electrical smell calls for cutting power and phoning a professional before the dishwasher runs again.

The distinction that actually matters isn't which cleaning product to try next. It's recognizing early which of these categories applies, so a few vinegar cycles don't turn into weeks of guessing before someone finally calls the right professional.