The E18 code on a Bosch washing machine means the machine has detected a blockage that stops it draining, usually in the pump filter or the drain hose, so it will not start or continue the wash. This guide to the Bosch washing machine E18 error explains what the code means, the safe checks Bosch says you can do yourself, and when to book an engineer.
Quick answer: E18 means your Bosch washing machine cannot pump water away, usually because the pump filter is blocked or the drain hose is kinked or blocked. You can safely unplug it, drain it, clean the pump filter and check the hose. If E18 comes back after that, book an engineer.
What Does the Bosch E18 Error Code Mean?
E18 is a blockage warning. Bosch’s own E18 support page says the machine shows E18 when it detects a blockage in the filter, or a blockage or kink in a hose, and that the machine will then fail to start or continue a wash cycle.
The page’s opening line mentions the water inlet hose, but every cause and fix Bosch lists for E18 concerns draining: a blocked drain pump and a kinked or blocked drain hose. In practice, E18 means water is not leaving the drum as it should. If the drum is still full of water when the code appears, that confirms a drain problem.
Code formats vary between Bosch models and display types, so check the troubleshooting table in your instruction manual if your display shows something slightly different.
What Causes the E18 Error?
Bosch names two main causes on its washing machine not draining page. In rough order of how often they happen:
- Blocked drain pump or pump filter. Coins, buttons, hair grips, fluff and small items of clothing collect in the filter and can stop the pump impeller turning.
- Kinked or blocked drain hose. The hose can fold when the machine is pushed back, or lint can build up inside it.
- Blocked siphon connection. Bosch’s steps include cleaning the siphon connecting piece, the spigot on the sink trap where the drain hose fits. Waste from the sink can block it.
- Pump or electrical fault. If the filter, hose and siphon are all clear and E18 returns, the pump itself or its control may have failed. This is a job for an engineer.
How Do You Fix the E18 Error Yourself?
These steps follow Bosch’s E18 guidance. Expect a lot of water: have towels, a shallow tray and a large container or bucket ready.
Clean the drain pump filter
- Switch off and unplug the machine. If it was running a hot wash, wait for the water to cool before draining.
- Open the service flap. It sits at the bottom front of the machine. Remove it as your manual describes.
- Drain the water. Use the small drainage hose behind the flap if your model has one. If not, unscrew the pump cover slowly over a large container, because more water can come out than you expect.
- Clean the pump. Remove the pump cover and clean the inside, the thread and the housing. Remove any foreign objects so that the impeller can turn freely.
- Refit the pump cover firmly. Screw it back in fully and refit the service flap.
- Leak test. Bosch suggests pouring 1 litre of water into the detergent drawer, then checking the pump cover for leaks. If it is dry, run the drain or pump programme.
Check the drain hose and siphon
- Keep the machine switched off and unplugged.
- Check for kinks. Ease the machine forward and make sure the drain hose runs smoothly with no folds.
- Remove the hose. Place a bucket underneath, loosen the hose clip at the siphon and carefully pull the hose off. Let any remaining water drain into the bucket.
- Clean the hose and siphon. Clear any blockage from the hose and from the siphon connecting piece.
- Test into the bucket. Plug in, hold the hose in the bucket and select the Drain programme. A strong flow means the hose and pump are clear.
- Reconnect and check. Switch off, refit the hose to the siphon, tighten the clip and check for leaks on the next wash.
Safety: Always switch off and unplug the washing machine before you open the service flap, touch the pump filter or remove the drain hose, and never open the pump cover during a cycle. Stop at the filter, hose and siphon checks. Do not remove the casing, test the pump or touch wiring or circuit boards: these jobs need a qualified engineer or Bosch’s own repair service.
When Should You Call an Engineer?
Bosch advises booking an engineer if cleaning the pump and drain hose does not clear E18. Call one, or use Bosch’s repair service if the machine is under warranty, when:
- The filter, hose and siphon are clear but E18 keeps returning.
- You hear no pump noise when the machine tries to drain, or a loud grinding or humming.
- The pump cover will not unscrew or is cracked.
- Water leaks from the pump cover or under the machine after you refit it.
- The sink waste or standpipe is blocked further down, in which case a plumber may be the right person.
Repair prices depend on the model and the part, so ask for a quote before work starts, and check your warranty before booking an independent repairer.
Which Bosch Codes Are Related to E18?
The table lists other Bosch washing machine codes from Bosch UK’s support pages that are often seen alongside drain problems.
| Code | What Bosch says it means | First step |
|---|---|---|
| E18 | Blockage in the filter or a blocked or kinked hose | Clean the pump filter, check the drain hose and siphon |
| E16 | The door is not locked properly | Open and close the door, remove laundry blocking it |
| E23 | The machine is leaking or there is water in the base plate | Turn off the supply tap immediately, then get help |
| E33 | Excess foam has been detected | Use less detergent next wash |
If your Bosch machine fills and drains but the drum will not turn, see our guide to the Bosch F21 error code.
How Can You Stop the E18 Error Coming Back?
- Empty pockets. Coins, keys, hair grips and tissues are the usual filter blockers.
- Use a wash bag. Socks, baby clothes and bra wires can slip through to the pump.
- Clean the pump filter regularly. Your instruction manual gives the recommended routine for your model.
- Keep the drain hose straight. Check it each time the machine is moved.
- Keep the sink trap clear. Food waste in a kitchen sink can block the siphon connection the machine drains into.
- Dose detergent correctly. Too much detergent creates foam, which Bosch flags with E33 and which slows draining.
Repeating failed cycles uses extra water and electricity. To see what each wash costs once the machine is working, use the electricity cost calculator with your machine’s wattage and your unit rate.
Bosch Washing Machine E18 Error FAQs
How do I reset E18 on a Bosch washing machine?
Clear the blockage first, because a reset will not drain the drum. Unplug the machine, clean the pump filter and check the drain hose and siphon. Then plug in, switch on and run the drain or pump programme. If the water drains, the code clears.
Where is the pump filter on a Bosch washing machine?
On most Bosch front loaders, the pump filter sits behind a service flap at the bottom front of the machine. Some models also have a small drainage hose behind the flap for emptying water first. Your instruction manual shows the exact layout.
How do I drain a Bosch washing machine showing E18?
Unplug it, open the service flap and use the drainage hose if fitted. Otherwise unscrew the pump cover slowly over a large container. Bosch warns to expect plenty of water, so keep towels and a bucket ready.
Why does E18 come back after I clean the filter?
If E18 returns, the blockage may be in the drain hose or the siphon connection instead, so check both. If they are clear too, the pump or its control may be faulty, and Bosch advises booking an engineer.
Can I open the door when E18 is showing?
If the door will not open while water is in the drum, do not force it. Drain the water through the service flap first, with the machine unplugged, then try the door again once the drum is empty. Forcing it can damage the lock.
Is E18 expensive to fix?
Often it costs nothing, because a blocked filter or kinked hose is the usual cause and you can clear both yourself. If the pump has failed, an engineer will need to replace it, and the price depends on your model, so ask for a quote first.
Checked October 2026. Sources: Bosch UK: E18 error code, Bosch UK: Washing machine not draining, Bosch UK: E16 error code, Bosch UK: E23 error code, Bosch UK: E33 error code.
