Bosch 500 Series Washer: Problems & Codes

The 500 Series is Bosch's 24-inch compact front-loader, and it fails in predictable ways once you know the platform. This guide lays out the ranked failure data, the error codes it throws, the OEM parts that go, and a plain fix-or-replace call by age.

Models this covers#

The same drum, pump, and control platform runs across the 500 Series line, so one repair playbook fits all three:

• WAT28400UC
• WAT28401UC
• WGA254AUCA

If your sticker starts with the same prefix but is not listed, the guidance still holds — Bosch reuses parts across variants in a series.

Spec at a glance#

Where these break, ranked#

1. E18 drain-pump blockage — 25%. Coins, clips, or lint reach the pump and stall it, and the compact housing clogs faster than a full-size machine would. Clearing the coin trap and pump often solves it before any part is needed.
2. E27 door-lock failure — 15%. The interlock stops confirming the door is shut, so the cycle never starts. The lock assembly is the usual replacement.
3. Door-boot gasket mold at the fold points — 14%. Moisture trapped in the tight compact boot grows mildew that carries a musty smell onto clean laundry.
4. E04 leak detection from over-dosing detergent — 10%. Too much HE detergent creates a suds overflow that trips the leak sensor; the fix is less soap, not a part.
5. Vibration during spin — 8%. Almost always leftover shipping bolts or tired shock absorbers letting the drum move.

How to read the fault first#

For a code not on the list below, pull power for 60 seconds (or flip the breaker), then restore it — transient faults often clear on a reset. If the same code returns immediately, it is a real fault and worth a proper diagnosis rather than repeated resets.

Error codes#

Each code opens a step-by-step diagnosis:

• Error E18 — drain restriction
• Error E27 — door lock
• Error E04 — leak / suds
• Error E02 — motor circuit

Parts that commonly fail#

The 500 shares its internals with the 800 Series, so the repair is identical — but a replacement 500 costs less, which nudges the math toward fixing rather than replacing.

Fix or replace?#

The simple rule: while the washer is under ten years old and a fix runs less than half the price of a comparable new machine, repair almost always wins. Past ten years, weigh the whole recent repair history — if you have spent on several major components already, a fresh machine with a new warranty starts to make sense. On this compact platform, though, a pump or a boot is inexpensive enough that repair usually stays the better value well into the unit's life.

Keeping it healthy#

• Run the tub-clean cycle monthly — compact drums grow odor faster than full-size machines.
• Wipe the door boot dry after each load and leave the door ajar between washes.
• Clean the coin-trap filter monthly through the front-access panel.
• Dose HE detergent lightly; a compact machine needs less than a standard washer.

Related guides#

• Bosch washer not draining
• Bosch washer leaking
• Bosch washer vibrating or shaking
• How to maintain a Bosch washing machine

Recall status#

No active recalls on the Bosch 500 Series as of 2026-05-28. Re-check your model at cpsc.gov now and then, since recalls can post at any time.

Book a Bosch 500 Series repair at /book — our trucks stock the common Bosch parts, so most visits are one and done.