Bosch won't drain on programmes
My Bosch excel 7 washing machine is flagging up E18 which is supposedly a blocked pump, I've made sure it's clear at the impeller end/filter and the sink end, it won't drain on programmes but WILL on the drain only function! My thoughts with reading this forum over the last few months is possibly a water sensor? Weight or flow or worse case the pcb?
We have cover for it with an extended cover but I'll get charged if no fault is found so want to fix it myself really, the machine is almost 5 years old, thanks for reading
Solution Summary
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This thread was marked as solved. Here's a summary of the problem and the fix, generated from the discussion below.
Bosch Excel 7 shows E18 and will only drain on drain-only cycle
- The problem
- A Bosch Excel 7 washing machine displayed fault code E18. The filter/impeller area and the sink waste end were reportedly clear. The machine would not drain during normal wash programmes, but it would drain on the separate drain-only function.
- Likely cause
- Most strongly supported diagnosis was an intermittent drain fault rather than a complete blockage, with possible causes suggested as a weak/intermittent pump, a drain hose installation or partial restriction issue, a pressure sensing problem such as a blocked pressure chamber or pressure switch hose, or less likely wiring/control issues. The exact cause was not confirmed.
- What fixed it
- Recommended action was to check the drain hose routing and for kinks or partial blockage, observe whether the pump runs during a failed programme, inspect the pump impeller for looseness or stiffness, and check pump wiring connections. If these checks did not identify the fault, the advice was that the pressure sensing system or control board might need further investigation. No completed repair was confirmed in the discussion.
- Checks to try
- Filter/impeller end checked clear
- Sink/drain end checked clear
- Suggested check of drain hose installation and bends
- Suggested check whether pump runs during failed programme
- Suggested inspection of pump impeller for looseness or stiffness
- Suggested check of pressure chamber or pressure switch hose
- Suggested check of pump wiring plug and harness
Safety: Isolate the washing machine from the mains before internal checks. Further diagnosis should be carried out by a suitably qualified appliance engineer.
1 Answer
Hi. On Bosch machines, E18 is usually a drain/pump-out problem, but the fact it will drain on a drain-only cycle is a very useful clue. It suggests the pump can work, so the fault may be intermittent or related to how the control is deciding to drain during wash programmes.
Before checking anything internal, isolate the washing machine from the mains.
1. Check the drain hose installation Make sure the hose isn’t pushed too far down the standpipe or connected in a way that could cause siphoning or poor flow. Also check for a partial blockage where the hose bends at the back of the machine.
2. Inspect pump operation during a failed programme When it should be draining on a wash cycle, listen carefully. - If the pump hums but water doesn’t move, there may still be a restriction or a weak pump. - If the pump doesn’t run at all on the programme, the issue is more likely control-related or sensing-related.
3. Check for an intermittent pump fault A pump can pass a drain-only test but fail when hot or under repeated use. Check the impeller for looseness or stiffness. If it feels worn or sloppy, the pump may be failing intermittently.
4. Check the pressure system A partially blocked pressure chamber or pressure switch hose can confuse the control about water level, affecting draining during programmes. This is a common enough cause, but it needs inspection inside the machine.
5. Wiring and connections Check the pump wiring plug and harness for loose or overheated connections.
If all of the above look fine, then yes, the pressure sensing system or control board become more likely, but I wouldn’t jump straight to the PCB. If you’re not confident with live electrical testing, it’s best left to an engineer. Any mains-related checks should be done by a qualified appliance engineer.
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This answer was generated automatically by the WhitegoodsHelp AI Assistant. It is not provided by an engineer or any other qualified person, may be inaccurate or incomplete, and is not professional or technical advice. Do not rely on it. Always use your own judgement and consult a qualified engineer before carrying out any electrical, gas or water work. Use is entirely at your own risk. See our full Terms of Use.
SAFETY FIRST: READ BEFORE ACTING ON THIS GUIDANCE
Never work on a live appliance
Always unplug it at the mains before going near it with any tools.
Never attempt gas work
By law, gas appliances must only be worked on by a Gas Safe registered engineer. If your fault involves gas, stop and call a professional. Do not attempt it yourself.
Watch for sharp edges
Outer panels are smooth, but internal parts have sharp machined edges. Wear protective gloves and arm sleeves.
Water appliances can leak
Turn off the water supply before disconnecting any hoses.
Know your limits
If you are not confident testing or working inside the appliance, stop and call a professional.
AI guidance, not guaranteed
This response is generated automatically by the WhitegoodsHelp AI Assistant. It is not professional or technical advice, may be incomplete or wrong, and must not be relied upon. Always use your own judgement and consult a qualified engineer before any electrical, gas or water work.
This is general information only and is not professional advice. The WhitegoodsHelp AI Assistant is not an engineer and is not qualified. See our full Terms of Use.
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