Bosch's troubleshooting table for dishes that are not clean enough on the SHXM4AY55N lists seven causes with fixes: incoming water not warm enough (run the hot tap first), spray arms blocked or misaligned, little or no spray from a clogged nozzle, clogged or misaligned filters, nested dishes or overfilled racks, an improper or ineffective cycle or detergent, and hard water making detergent less effective. Bosch designed the filter system so normally attached food soils need no pre-rinse, just scraping. The Auto cycle is the smartest for mixed loads, and Heavy is for baked-on food or grease.
Differential
Likely causes of “Bosch dishwasher does not clean dishes”, and how to tell them apart
- 1
Blocked or clogged spray arms
What separates it Dishes are dirty in the same rack every time
How to confirm Make sure both spray arms rotate freely and clean the nozzles and filters
- 2
Filters clogged or misinstalled
What separates it Gritty film on dishes and debris in the tub
How to confirm Clean the filters and check they are correctly installed and locked
- 3
Nested or overfilled racks
What separates it Food soils remain where dishes touched because the racks are nested or overfilled
How to confirm Space dishes apart so the jets reach every surface and racks are not overfilled
- 4
Hard water or the wrong cycle and detergent
What separates it A dull film and food remains on baked-on items
How to confirm Install a softener, choose a more intensive cycle and use an appropriate detergent
Before you touch a setting
Record this first — changing settings destroys the evidence
- Which cycle and options were used and the detergent
- Where on the racks dishes stayed dirty
- When the filters were last cleaned
Try in this order
0 of 5 completedWarm the water and scrape
ReversibleBefore starting, run the hot faucet closest to the dishwasher. Scrape food off dishes and use less intensive cycles for light soil.
Check the spray arms
ReversibleMake sure the upper and lower spray arms can rotate freely, and check them for grease and limescale deposits. Unscrew the upper arm and pull off the lower arm to inspect them.
Clean the filters
ReversibleUnscrew the Large Object Trap and remove the filter system, take the micro filter out of the fine filter, rinse under running water and clean with a soft brush; no abrasive brushes or steel wool.
Space dishes apart
ReversibleSpace dishes so spray jets reach every surface and dishes do not contact each other, and do not overfill the racks.
Choose the right cycle and detergent
ReversibleHeavy is best for baked-on food and grease; Auto senses soil and suits mixed dishware. With hard water install a softener and use a more intensive cycle.
Model-specific
What is true of this model and not of its siblings
- The filter system
- The Bosch filter system filters 100 percent of the water entering the spray arms. The Large Object Trap prevents objects from damaging the pump or clogging the drain, the Flat Fine Filter keeps food out of the wash chamber and directs particles to the micro filter, and the Micro Filter directs the smallest particles to the household drain.
- Parts for this problem on the SHXM4AY55N (RepairClinic, 2026-09-21)
- briggs & stratton original equipment 491588s air, part number 491588S, at $8.80.
- Other models this page answers
- These steps also fit models SHE3AEM5N, SHE53B75UC, SHS43CF5N, SHP65CM5N, SHP865WD5N, SHX78CM5N, SHV9PCM3N.
Stop boundary
When this stops being a self-service repair
- !If dishes stay dirty with free spray arms, clean filters and hot water, contact Bosch Customer Support on 1-800-944-2904
- !If E:22 shows, follow the filter fix, and clean the filter system
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
Do I pre-rinse?+
No. Bosch says do not pre-wash items with loosely attached food soil; scrape food off.
What are the three filter parts?+
A large object trap, a flat fine filter and a micro filter.
Which cycle for baked-on food?+
Use the Heavy cycle for baked on food.
What if the water is hard?+
Install a water softener and choose a more intensive cycle.
How do I clean the spray arms?+
Rinse them and use a toothpick for blocked holes; unscrew the upper arm and pull off the lower one.
What does the AquaSensor do?+
It measures the clarity of rinse water and replaces it with fresh water if it is not yet clear.
Can hand dish soap be used?+
No. Use only detergent designed for dishwashers.