If a Bosch WAT28400UC leaves water in the drum, Bosch's troubleshooting says the causes are excessive suds (usually too much detergent or non-HE detergent: use less and only HE), a blocked pump (check and clean the drain pump, the water drain hose and/or the drain pipe), and a blocked drain hose or drain pipe (clean it). The error message E:18 is the drain fault: too much detergent or non-HE detergent (the foam symbol shows at the end of the cycle), or the pump is blocked; clean the washer drain hose and drain pipe and, if necessary, perform pump maintenance. The pump is reached through the service cover at the bottom front.
Differential
Likely causes of “Bosch 300 Series WAT28400 front-load washer will not drain or stops with water inside”, and how to tell them apart
- 1
A blocked drain pump
What separates it E:18 shows and there is water in the drum because the drain pump is blocked
How to confirm Clean the pump housing and check the impeller turns freely
- 2
A clogged drain hose or drain pipe
What separates it The water drains slowly or not at all because the drain hose or the drain pipe is clogged
How to confirm Clean the hose and the pipe, and then run a drain
- 3
Excess suds
What separates it The foam symbol shows and the load is wet because of excess suds
How to confirm Use less HE detergent, and run a rinse
- 4
Lint or debris in the pump
What separates it Fluffy fabrics are a listed cause because lint or debris is in the pump
How to confirm Check the drum and remove debris after each load
Before you touch a setting
Record this first — changing settings destroys the evidence
- Whether E:18 or the foam symbol showed
- Whether the sound of water pumping can be heard
- How much water is left in the drum
Try in this order
0 of 5 completedTry the Drain program
ReversibleTurn the selector to Drain and touch Start/Pause; a totally blocked pump will not drain.
Turn off and unplug
ReversibleTurn off and unplug, by shutting off the tap, switching off the appliance and unplugging it.
Open the service cover and drain
ReversibleLoosen the screws, remove the protective film, and use the pull-out drain hose to drain up to 5.3 gallons into a container.
Clean the pump
ReversibleTurn the pump cover counterclockwise; a little water flows out; clean the housing and check the impeller turns freely; refit the cover tightly with the handle vertical.
Reassemble
ReversibleRefit the protective film with both screws and snap the service cover in place; pour 1 liter of water into chamber II and run Drain.
Model-specific
What is true of this model and not of its siblings
- When to clean the pump in Bosch's words
- It may be necessary to clean the drain pump if the washer fails to drain: the sound of water being pumped cannot be heard when the washer should be draining and other nearby drains such as a sink are draining properly. The pump can be blocked by loose debris, which is a good reason to check the drum and remove visible debris after each load, and fluffy fabrics may also cause blockage.
- What E:18 looks like
- E:18 displays with the foam symbol at the end of a cycle for suds, or on its own if the pump is blocked. Bosch's measures are: use less detergent and only HE detergent for suds, clean the drain hose and drain pipe, and perform pump maintenance to clear the blockage. If the code appears again after switching off for 5 seconds and on, call customer service.
- Parts for this problem on the WAT28400 (RepairClinic, 2026-09-20)
- drain pump, part number 00145753, at $155.35; filter-fluff, part number 00647920, at $33.75; hose-drain, part number 00656689, at $31.67.
- 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 E:18 returns after cleaning the pump and hose, call Bosch customer service on 1-800-944-2904
- !If the pump motor hums but water does not move, service is needed
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
What does E:18 mean on a Bosch washer?+
The washer detected a drain fault: too much or non-HE detergent, or a blocked pump.
Where is the drain pump?+
Behind the service cover at the bottom front; the pull-out drain hose is in the opening.
How much water can the hose drain?+
Up to 5.3 U.S. gallons (20 liters).
Why pour a liter of water into chamber II afterwards?+
To stop detergent flowing unused into the drain during the next wash.
How often should I clean the pump?+
When the washer fails to drain or you cannot hear water being pumped.