Why does my dishwasher smell bad?

A funky smell coming from the dishwasher is almost always one of two things: trapped food debris in the filter, or gunk building up on the door gasket. Both are common, both are harmless to fix yourself, and both are easy to keep from coming back.

Start with the filter

Most modern dishwashers have a removable filter in the bottom, under the lower spray arm. It catches food particles so they don’t recirculate—but when it clogs, that trapped food sits in warm, damp darkness and starts to smell. Twist it out, rinse it under hot water, and scrub gently with an old toothbrush. Doing this every few weeks prevents most odor problems outright.

Then check the gasket and edges

The rubber seal around the door, and the lip just inside it, collect grease and food film that the wash cycle never reaches. Wipe them down with warm soapy water. While you’re there, check the spray-arm holes for anything blocking them.

Reset it with a cleaning cycle

• Run an empty hot cycle with a cup of white vinegar on the top rack to cut grease and odor.
• For stubborn smells, sprinkle baking soda on the bottom and run a short hot cycle afterward.
• Going forward: scrape plates before loading, and run the kitchen tap hot before starting so the wash begins with hot water.

If the smell is more like sewage than sour food, the cause may be the drain hose or an air gap rather than the dishwasher itself—worth a look before you assume the appliance is the problem.