Bosch's own page on a smelly dishwasher says the cause is food particles and debris stuck in the filter with every cycle, and its fixes are the ones the SHXM4AY55N manual gives: run the Bosch dishwasher cleaner a few times a year for greasy residues (one box in the bottom, hottest and longest cycle), use the Bosch descaler for hard water deposits and limescale, clean the filter regularly with soap and a soft brush, and check the spray arms are not clogged, using a toothpick for blocked holes. Clean the door seal with a damp cloth, since a soiled seal can hold odors, and run the dishwasher more often.
Differential
Likely causes of “Bosch dishwasher smells bad or musty”, and how to tell them apart
- 1
Food debris in the filter and sump
What separates it A sour smell that is strongest when the door opens
How to confirm Clean the filter system and the sump regularly, to remove food debris
- 2
A soiled door seal
What separates it Odor from the rubber edge and food traces along it
How to confirm Clean the door seal regularly with a damp cloth
- 3
Residual standing water or a drain fault
What separates it There is stagnant water after a cycle because of residual standing water or a drain fault
How to confirm Clear the drain line or hose; check it was installed with a high loop
- 4
Not using rinse aid or the proper detergent
What separates it There is a musty smell with residue on dishes because rinse aid or the proper detergent is not used
How to confirm Use rinse aid and the proper detergent, and run the dishwasher more frequently
Before you touch a setting
Record this first — changing settings destroys the evidence
- Where the smell is strongest, at the tub, filter or door
- When the filter and door seal were last cleaned
- Whether water is left after a cycle
Try in this order
0 of 5 completedClean the filter
ReversibleRemove the filter system and clean the filters under running water with soap and a soft brush. Bosch recommends cleaning after loads with heavy starch or lots of food soils.
Clean the door seal and sump
ReversibleWipe the door seal with a damp cloth to remove food particles that can cause odor, and clean the sump as needed.
Use dishwasher cleaner and descaler
ReversibleAdd one box of Bosch dishwasher cleaner to the bottom of the empty dishwasher and run the hottest, longest cycle. Use the descaler for limescale in the same way, then run another wash cycle.
Check the spray arms
ReversibleRun the arms under water to see if any holes are blocked. Use a toothpick to loosen debris in the holes.
Run it regularly
ReversibleRun the dishwasher more frequently, do not leave soiled dishes for long, and leave the door slightly open when leaving for a vacation.
Model-specific
What is true of this model and not of its siblings
- Cleaning cautions
- Bosch says never to use a steam cleaner, not to use sponges that scratch surfaces or bleach-based wipes that can damage the surface or printing, not to use stainless steel polish on black stainless or anti-fingerprint finishes, and to clean the outer edges of the inside door panel regularly to remove debris that collects from loading.
- Parts for this problem on the SHXM4AY55N (RepairClinic, 2026-09-21)
- briggs & stratton original equipment 491588s air, part number 491588S, at $8.80; tecumseh fuel line clamp., part number 26460, at $1.75; carburetor gasket, part number 33263, at $1.56.
- Other models this page answers
- These steps also fit models SHE3AEM5N, SHE53B75UC, SHP65CM5N, SHP865WD5N, SHP78CM5N, SHX78CM5N, SHV9PCM3N.
Stop boundary
When this stops being a self-service repair
- !If the smell persists after cleaning the filter, seal, spray arms and running cleaner, contact Bosch Customer Support on 1-800-944-2904
- !If the smell is burning or electrical, stop the dishwasher and switch off the power
Evidence ledger
Sources behind this answer
Bosch's own list of dishwasher error codes with the fixes for E15, E18, E22, E24, E25 and E27.
Bosch's own owner-support articles for a dishwasher that will not drain, will not dry or smells.
Bosch's own specification sheet for this model.
Parts and list prices as shown on RepairClinic's parts search for this model number on 2026-09-21.
Exact questions
Common questions
Why does my dishwasher smell?+
Food particles and debris get stuck in the filter with every cycle.
How do I clean a smelly dishwasher?+
Use Bosch dishwasher cleaner, descaler and clean the filter and spray arms.
Is a new dishwasher smell normal?+
Water testing is done in the factory, so some water may appear at purchase, which may create an odor.
Can a dirty seal cause smell?+
Yes. A soiled door seal may not seal properly and can hold odors.
Should I leave the door open?+
Bosch says to leave it slightly open when away and not to leave soiled dishware in the unit.
What if a drain hose is blocked?+
Clear it, and make sure it was installed with a high loop.