Most dishwasher odors come from food trapped in the filter, water sitting in the sump, or the drain letting dirty water flow back from the sink or disposal. The kind of smell and where it's strongest point you to the right fix.
Safety first: Unplug the dishwasher or switch off its breaker before reaching into the bottom, and watch for broken glass around the filter.
Follow the diagnostic path
Step 1: Have you cleaned the filter in the past month?
If yes: Go to Step 2.
If no: Start here. On most current models the filter twists out from the floor of the tub. Rinse it, scrub the mesh with a soft brush, and lock it back in.
Step 2: Is there more than a little water sitting in the bottom after a cycle?
If yes: The dishwasher isn't draining fully, and that water goes stale. Check the filter, look for a kinked drain hose under the sink, and make sure the disposal inlet isn't clogged. A small amount of water around the sump is normal on many models.
If no: Go to Step 3.
Step 3: Does the smell get worse after you run the disposal or the sink drains?
If yes: Dirty water may be flowing back into the dishwasher. The drain hose usually needs a high loop under the counter or an air gap, depending on how it was installed. A technician or plumber can correct the routing.
If no: Go to Step 4.
Step 4: Is it a rotten-egg smell that also comes from the hot water taps?
If yes: The source is the water or the water heater, not the dishwasher. If you're on a well, our guide to well water appliance problems explains the sulfur angle.
If no: Go to Step 5.
Step 5: Is the smell musty and strongest around the door edges?
If yes: The door gasket and the bottom edge of the door collect grime the spray arms never reach. Wipe them with warm soapy water and leave the door cracked open after cycles.
If no: A worn pump, a hidden clog or debris in the sump may be the cause. A technician can open it up.
What your answer points to
| What you found | Most likely cause | DIY or technician |
|---|---|---|
| Food-coated filter | Trapped debris | DIY cleaning |
| Standing water | Partial drain blockage | DIY first, then technician |
| Worse after disposal runs | Drain backflow | Technician or plumber |
| Rotten-egg smell from taps too | Water supply or water heater | Plumber or water-treatment pro |
| Musty door edges | Grime on gasket and door | DIY cleaning |
Stop and call a technician if
- •Water stays in the tub after a full cycle.
- •The smell is like burning plastic or hot wiring.
- •Dirty water appears in the tub when the sink drains.
Keep it from coming back
- •Clean the filter every few weeks.
- •Scrape plates, and run the sink's hot water before starting.
- •Run a dishwasher cleaner as your manual recommends.
Owen's shop tip: I always look at the drain hose under the sink. If it lies flat on the cabinet floor with no loop, I know where half the smell is coming from.
Clean filter, good drain loop and the smell is still there? ProFix Boston can open up the sump and pump; call (617) 812-1425 or visit our dishwasher repair service.