Step-by-Step DIY Fix Guide
- SAFETY: Switch off and unplug. Caution — drain water may be hot.
- Check drain hose for kinks and straighten.
- Verify hose end is no higher than 39 inches.
- Check and clear the sink drain.
- Clean the pump filter.
- Restore power and run a drain cycle.
If it's still not draining
- If the drain path looks clear but the code returns, the issue is more likely in the pump path or another less accessible restriction.
- If the door closes normally but the warning keeps returning, the latch or switch path becomes more likely than a simple alignment issue.
- If airflow still seems weak after the basic checks, the fan path or a deeper obstruction becomes more likely.
What This Error Means
F18 on your Bosch washing machine means: Same fault as E18 — drainage hose blockage or positioning issue on F-code models. The machine detects this condition via its sensors and stops the current cycle to prevent further damage. The error will remain until the underlying cause is resolved.
The most frequent cause is drain hose kinked behind machine. Work through the causes listed below in order — the first cause is the most likely and the most straightforward to check.
Error F18 is DIY-safe for most homeowners. The fix typically takes under 30 minutes and requires no specialist tools. Follow the steps below exactly — skipping steps is the most common reason the error returns.
The most visible symptom is standing water in the drum at the end of a cycle. Do not run another cycle until the blockage is cleared — standing water stresses the door seal and pump motor.
What users usually notice before this code
Bosch washing-machine warnings like this often appear after a fill problem, a drain slowdown, a badly balanced load, or a startup sequence that did not settle cleanly.
Common misdiagnoses
- Assuming the display code proves one exact failed part before the safe first checks are done.
- Blaming a pump or valve first when a blocked path, filter, hose, or household plumbing issue is still possible.
- Replacing a lock or latch too early when alignment, trapped laundry, or startup conditions may still explain the warning.
Most Likely Cause by Symptom
The Bosch washing machine may stop, pause, or refuse to complete the cycle normally.
Likely cause: Drain hose kinked behind machine
Check first: SAFETY: Switch off and unplug. Caution — drain water may be hot.
Water may remain inside the drum at the end of the cycle.
Likely cause: Blocked sink drain or standpipe
Check first: Check drain hose for kinks and straighten.
The appliance may fail to start because the door or lock state cannot be confirmed.
Likely cause: Clogged pump filter
Check first: Verify hose end is no higher than 39 inches.
Common Causes
- Drain hose kinked behind machine
- Blocked sink drain or standpipe
- Clogged pump filter
- Hose positioned too high
What Not to Do
- Caution — hot water risk
- Do not position hose too high
Model and Display Variation Notes
Model-family notes
- Bosch washing machine display wording and code formats can vary by series.
- If your model behaves differently, check the owner manual before trying any deeper maintenance step.
Display and panel differences
- Panel wording can vary by series, so confirm the exact code pattern before buying parts.
Parts, Tools and Service Options
Common parts
- Drain hose ($15–$35)
Manual and model check
Check your exact model and manual before ordering any Bosch washing machine parts.
Suggestions in this section are organized to support the troubleshooting flow first. Any future affiliate relationships should be disclosed clearly.
When Not to Keep Troubleshooting
Hose and filter clear but F18 persists
How to Prevent It Recurring
- Check drain hose routing
- Clean pump filter every 3 months
Related Error Codes
Helpful guides for this problem
Guide
What to check before replacing a dishwasher drain pump
The checks worth doing before you blame the drain pump and spend money on a fix that may not be the real problem.
Guide
Before calling appliance service: the safe checks worth doing first
The simple checks that can save time, money, and a messy support call before you commit to service or parts.
Guide
How to tell if a dishwasher problem is drainage or leak-protection related
How to tell whether a dishwasher water-related warning is about drainage or a more cautious leak-protection stop.
When not to keep pushing DIY troubleshooting
Use the code page for one careful first pass, then stop if the same warning returns or the appliance still cannot get back to normal operation.
Extra notes
- This page is based on Bosch support material and stays conservative where model-specific guidance may vary.
- The goal is to help you identify safe first checks before you move into parts, service, or model-specific manual lookup.
Source and model notes
Last reviewed: 2026-04-07
Based on: Based on Bosch support material and edited into consumer-safe guidance for the exact code family on this page.
Model coverage note: Bosch washing machine code meanings can vary by series, control panel, and model family, so use this page as a safe starting point rather than a replacement for the model-specific manual.
Important: FixThisError is an independent guide, not the manufacturer. Use your model-specific manual when the panel wording or behavior differs.
Always disconnect power before inspecting appliances. If unsure, contact a licensed appliance technician.