What Does Error Code E18 Mean on a Bosch Washing Machine?
Clean the drain filter located behind the small access panel at the bottom front of the machine — remove any debris or blockages, refit the filter firmly, and run a short spin cycle to confirm the fault clears (takes about 10 minutes).
Fault description
Error code E18 is Bosch's way of telling you that water is not leaving the drum as it should. When the machine attempts to drain — typically at the end of a wash or rinse cycle — it expects the drum to empty within a set time window. If that doesn't happen, the control board triggers E18 and halts the programme to prevent flooding or motor damage.
You'll usually notice the machine has stopped mid-cycle with water still sitting in the drum, and the display is showing E18 or a flashing indicator pattern depending on your model. The door will remain locked while water is present, which is a safety feature rather than a separate fault.
The good news is that the majority of E18 errors are caused by a blocked filter or a simple hose issue — both of which are straightforward to resolve at home without any specialist tools.
Causes
- Blocked drain filter — The drain filter catches lint, coins, hair grips, and other small items before they reach the pump. Over time it becomes clogged and restricts water flow enough to trigger E18. This is by far the most common cause.
- Kinked or blocked drain hose — The corrugated drain hose running from the back of the machine to your standpipe or sink can become kinked if the machine has been pushed too close to the wall, or partially blocked by debris. Either condition prevents water from exiting freely.
- Blocked standpipe or household drain — If the standpipe or sink drain that the washing machine empties into is itself blocked, water has nowhere to go and backs up into the machine. This can look identical to a machine fault but the problem is actually in your plumbing.
- Faulty drain pump — The drain pump is the component that actively forces water out of the drum. If the pump impeller is jammed by a foreign object, or the pump motor has failed electrically, the machine will not drain regardless of how clear the hose and filter are.
- Pump wiring or connection fault — Loose or corroded wiring between the control board and the drain pump can interrupt the signal that tells the pump to run. The pump itself may be perfectly functional but simply not receiving power.
- Control board fault — In rare cases the main control board fails to send the correct drain command even though all mechanical components are working. This is uncommon and is usually only diagnosed after all other causes have been ruled out.
Step-by-Step Fix
- 1
Switch off and unplug the machine
Before doing anything else, turn the programme dial to off and unplug the appliance from the mains. This is essential for safety, particularly when you are about to handle water and access internal components. Place a few old towels on the floor in front of the machine.
- 2
Drain residual water via the emergency drain hose
Open the small access flap at the bottom front of the machine. You will see a short rubber emergency drain hose clipped next to the filter cap. Pull it out, remove the plug from its end, and direct it into a shallow bowl or tray. Let the water drain out completely before proceeding — you may need to empty the bowl several times.
- 3
Clean the drain filter
Once the water is out, slowly unscrew the filter cap anticlockwise. Have a towel ready as a small amount of residual water will spill. Pull the filter out fully and rinse it under a tap, removing all lint, debris, and any foreign objects. Also reach into the filter housing with your fingers and check nothing is lodged inside. Refit the filter and tighten it firmly — a loose filter cap causes leaks.
- 4
Check the drain hose for kinks or blockages
Pull the machine gently away from the wall and inspect the full length of the corrugated drain hose. Straighten any kinks and ensure the hose is not compressed against the wall. If you suspect an internal blockage, disconnect the hose from the standpipe and blow through it or flush it with water to confirm it is clear.
- 5
Check the standpipe or sink drain
Pour a bucket of water directly into the standpipe or sink that the machine drains into. If it drains slowly or backs up, the household drain is the problem rather than the machine. Use a drain unblocker or contact a plumber to clear it before running the washing machine again.
- 6
Check the pump impeller for obstructions
With the filter removed, shine a torch into the filter housing and locate the pump impeller — it looks like a small plastic fan. Try turning it with your finger; it should rotate freely with slight resistance. If it is completely jammed, there is likely a foreign object lodged behind it. Use long-nose pliers to carefully retrieve any obstruction.
- 7
Plug in, run a test cycle, and check for recurrence
Refit everything securely, plug the machine back in, and select a short spin or rinse-and-spin programme. Watch the machine through the cycle to confirm it drains fully and the E18 code does not return. If the error reappears after completing all the steps above, the fault is likely internal and will need professional diagnosis.
Affected models
Select your model to see its full troubleshooting page.
When to call a service technician
If you have cleaned the filter, confirmed the hose is clear, and verified the household drain is working, but E18 continues to appear, the drain pump itself has most likely failed mechanically or electrically. A jammed impeller that cannot be freed by hand, a pump that makes no sound at all during the drain phase, or a pump that hums but does not move water are all signs the pump needs to be replaced.
You should also contact a service technician if you notice any burning smell coming from the machine, if the wiring connections to the pump look burnt or corroded, or if the error code returns immediately after a pump replacement — as this may point to a control board fault that requires specialist diagnostic equipment.
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Frequently Asked Questions
Can I still use my Bosch washing machine while it is showing E18?
No — you should not run a cycle while E18 is active. The machine has stopped because it cannot drain, and forcing another cycle risks leaving a drum full of stagnant water, potential leaks, or damage to the pump motor. Resolve the drainage fault first, then resume normal use.
Will turning the machine off and on again clear the E18 code?
A power reset may temporarily clear the code, but if the underlying blockage or fault is still present, E18 will return as soon as the machine tries to drain again. Always address the root cause rather than relying on a reset.
How do I know if my drain pump has failed rather than just being blocked?
During the drain phase, listen carefully to the machine. A working pump makes a distinct low hum or whirring sound. If you hear nothing at all, the pump motor may have failed electrically. If you hear a hum but no water moves, the impeller is likely jammed or the pump is seized. In either case, the pump will need to be inspected or replaced.
My filter was completely clean — why am I still getting E18?
A clean filter rules out the most common cause, but E18 can also be triggered by a kinked drain hose, a blocked household standpipe, a failed pump, or a wiring fault. Work through the remaining steps in the guide systematically — particularly checking the standpipe and listening to the pump during a drain attempt — before concluding the fault is internal.
How often should I clean the drain filter on my Bosch washing machine?
Bosch recommends cleaning the drain filter approximately every three months under normal use. If you wash heavily soiled items, pet bedding, or large loads frequently, check it monthly. Regular cleaning takes less than five minutes and is the single most effective way to prevent E18 and extend the life of your drain pump.