For a Bosch WAT28400UC dispenser that leaves residue or does not rinse the softener compartment well, the manual's cleaning steps are: open the detergent dispenser tray fully, press down on the drawer catch and pull the tray from the housing, lift the insert out of the tray, hold the insert and tray under warm running water and wipe away residue, then refit the insert and slide the tray back in, closing it securely. Bosch also says never to run the washer without the tray in place and to keep it completely closed. Its troubleshooting table blames detergent residue on damp or lumpy dry detergent or excess liquid detergent; use the dosing cup for liquid detergent and clean and dry the dispenser.
Differential
Likely causes of “Bosch 300 Series WAT28400 front-load washer does not dispense”, and how to tell them apart
- 1
Damp or lumpy dry detergent
What separates it Detergent residue remains in the dispenser because of damp or lumpy dry detergent
How to confirm Use dry detergent that is loose; clean and dry the dispenser
- 2
Excess liquid detergent
What separates it There is residue and slow flushing because of excess liquid detergent
How to confirm Use the dosing cup and the recommended amount of HE detergent
- 3
Softener compartment not rinsed out
What separates it Softener is left in the tray because the softener compartment is not rinsed out
How to confirm Clean the tray and insert under warm running water
- 4
A tray that is not fully closed
What separates it There is early dispensing or a leak because the tray is not fully closed
How to confirm Keep the tray completely closed, and check that it is seated
Before you touch a setting
Record this first — changing settings destroys the evidence
- Which compartment has residue and what product is in it
- Whether the detergent is damp or lumpy
- When the tray was last cleaned
Try in this order
0 of 5 completedOpen the tray fully
ReversibleOpen the tray fully, by pressing down the drawer catch and pulling the tray out of the housing.
Remove the insert
ReversibleRemove the insert, by grasping it and pulling it upwards out of the tray, and then test again to see whether it helped.
Rinse them
ReversibleRinse them, by holding the insert and the tray under warm running water and lightly wiping away residue.
Refit and close
ReversibleRefit and close, by attaching the insert, sliding the tray back and closing it securely.
Dose correctly
ReversibleDose correctly, by using the dosing cup for liquid detergent and following the HE detergent instructions.
Model-specific
What is true of this model and not of its siblings
- Foam through the dispenser
- If foam comes out of the detergent dispenser drawer, too much detergent or non-HE detergent was used and the pump was unable to pump out the increased suds. Bosch's immediate fix is to mix 1 tablespoon of fabric softener with 1/2 liter (1 pint) of water and pour the mixture into the detergent compartment, not with waterproof fabrics, and to use less detergent for future loads.
- Detergent residue on laundry
- Some phosphate-free detergents contain water-insoluble ingredients that may appear as light spots on the laundry. Bosch says to brush them off when the laundry is dry or to run the Rinse program. It is a detergent effect rather than a dispenser fault, and switching detergents is the durable cure.
- Parts for this problem on the WAT28400 (RepairClinic, 2026-09-20)
- dispenser, part number 11051387, at $177.22; water inlet valve, part number 00635399, at $146.39.
- Other models this page answers
- These steps also fit the 300 Series WGA12400UC washer, 800 Series WAW285H2UC washer, 800 Series WGB24600UC washer.
Stop boundary
When this stops being a self-service repair
- !If detergent does not wash away at all after cleaning and checking the water supply, call Bosch customer service
- !If the tray is cracked, stop using the washer and call service
Evidence ledger
Sources behind this answer
Bosch's own US owner-support pages for washer error codes and self-help.
Parts and list prices as shown on RepairClinic's parts search for this model number on 2026-09-20.
Exact questions
Common questions
How do I clean the Bosch WAT28400UC dispenser?+
Press the drawer catch, remove the tray and insert and rinse them under warm running water.
Why is there residue in the dispenser?+
Damp or lumpy dry detergent or too much liquid detergent.
Can I run it without the tray?+
No; Bosch says never to operate the washer without the tray in place.
What if detergent is not washed away?+
Check Start/Pause was touched, the taps are on, the hoses are not kinked and the strainers are clean.
What about softener compartment?+
Clean it if it is not rinsed out well enough.
What detergent should I use?+
Only HE detergent, dosed with the cup.
Where do I clean the drain pump?+
Follow the pump maintenance steps in the manual, and switch off and unplug the washer first.