Dishwasher Help Forum

If anybody can advise on a problem I have with a Siemens sn26t252gb/01 Id be very grateful, Ive tried everything I can think of and made very little progress.
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When first started the machine pumps out any remaining water as normal, Then there is a short gap. Then one of 2 things happens: either I hear water coming in and I know its going to work, or more usually it sounds like the pump is trying to drain again and it does that for 1 min until it stops completely with a beep

When this happens its shows both error code E24 (blocked drain) AND the water supply tap symbol is lit. Never one or the other, always both together.

Ive cleaned the filters - including the one in the aquastop valve - and checked the impellor to make sure its moving freely. I have replaced the drain hose, and made sure the hoses arent kinked. The drain pump seems to be working without a problem. Ive increased the water pressure at the mains and checked for leaking water in the base of the machine but its dry.

I don't think its the aquastop valve because as far as I can see on this machine the matrix is usually already full of water before it starts, the problem seems to be the point when that water is supposed to go into the machine.

I have ( accidentally) discovered a workaround: When it tries to drain for that second time I interrupt the program by opening the door then closing it again - then I hear a short 'pssht' as water moves somewhere inside and it all works fine.

What does it all mean? Any suggestions at all gratefully received.

It's a drain pump problem you've got so you need to closely inspect the pump impeller to ensure it's clear. Refit the pump cover and the see if that sorts the problem? If it doesn't then chances are the pump needs replacing.


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Thanks Martin, I'll check over it again and report back, though from what Ive seen so far it always pumps out without a problem - in fact very often thats the only thing it DOES do!

Hello again .
Ive run some checks on the drain pump - firstly by pouring water coloured with food dye into the bottom of the machine several times then starting a program - I can see it whooshing through the drain hoses without a problem each time.

Ive also removed the pump altogether and had a look - the impellor moves freely and the sump and pipes seem fine.

Do you still think its a drain pump problem? ...in which case it may be time to bite the bullet and try a new one as you suggest.

sbridge wrote:Do you still think its a drain pump problem? ...in which case it may be time to bite the ubullet and try a new one as you suggest.

Not really, from what you say it appears OK so maybe something else is causing the E24 error? I've been told a blockage in the circulating pump can also throw up this error, though I haven't come across it myself. The non-return valve could also be an issue apparently. So best see how you get on running a full cycle?


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Excellent, many thanks, I'll check the circulation side of things next

Hi Martin

I have followed your very helpful advice and run some cycles, checked the circulation, and watched the water travelling around the pipework. I havent made any progress towards a remedy but I have been able to get a little closer to the cause ( I hope)

I've decided its easier to understand If I turn the problem completely on its head and look at when it works rather than why it stops, so let me describe the problems as follows : This machine works perfectly - every time, without fail - from beginning to end, on every program without any issues whatsoever, and there seems to be nothing wrong with any of the parts. However it will ONLY work properly if I open and then close the door at a particular point at the beginning of the cyle. That's all, just open and close the door again.

From studying the cycle it seems that what SHOULD happen is that at the start the drain pump hums for a 30secs or so and water is pumped out, then there is a different hum for 30 secs ( circulation pump?) then the aquastop lets in water, the little flow meter goes round and every thing is fine.

What ACTUALLY happens is that the aquastop does NOT activate. At that point the drain pump comes back on for 30 seconds then the machine fails with the 2 error codes mentioned.
It is during that second draining that I open and close the door - and that off/on switch seems to trigger the missing impulse to the Aquastop because if I do that whilst the pump is trying to drain it the valve opens, water pours in and everything is fine

My guess is that its not the Aquastop thats the problem, its the signal it should be getting thats the problem .

Any clues here that help towards a diagnosis?

I'm still pointing the finger of blame on the drain pump. The reason for this conclusion is straightforward enough when you realise the exact function of the pump. It has a DC motor and is controlled by the main circuit board. The circuit board constantly measures the current drawn by the pump and if it goes beyond the preset parameters the circuit board stops and then starts the pump (on-off-on-off....etc) in the hope of clearing what it believes is a blockage. If it fails to detect a reduction in current drawn then the circuit board shuts down and displays the E24 error.

Based on that knowledge I would conclude that the pump itself is worn and draws too much current from a cold start. Once it gets up and running it works just fine. Until the next time when it has not been used for a number of hours (between wash cycles).

Opening and closing the door may simply cause an interruption in the drain pump control process sufficient to override the problem.

That's my theory anyway and I'm sure a new drain pump will cure all.

right!...here goes

Two things to check . Is the impellor access cover on properly ? If it is then you may need to check the non-return valve which is situated in the sump between the drain pump and drain hose . A foreign object/blockage in the non-return valve , stopping it from closing corretcly can cause E:24 faults.

Thanks for that, Ill check both of those when i swap the drain pump over. Will report back .

Have fitted a new drain pump today. The most immediately noticeable difference is the new pump sounds completely different to the old one, which by comparison does sound a bit rattly. Non-return valve and impellor cover both checked and seem fine. Am going to run the programs over the next few days and will report back.

No...things have improved and it now works properly more often than not ( and the drain pump does sound much happier) but I'm afraid that quite regularly it STILL fails to trigger the water ingress after the initial draining, unless I interrupt it by opening the door....its very frustrating

Anything more I can try?...or is it time to get a professional in to have a look - will check your recommended engineers -

I know this sounds stupid but, give it a gentle tap, and I do mean gentle, in-between where the door catch and the row of six buttons are... If it starts when you tap it, you may have a sticky relay on a pcb.

ah, thats interesting....I'll give that a try. thanks Allsorts