Fixing Bosch Dishwasher Draining Issues - Dengarden - Home and Garden
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Fixing Bosch Dishwasher Draining Issues

I found dirty water pooled inside our Bosch dishwasher: Here's how I repaired the problem and a DIY troubleshooting guide for fixing yours.

See that pool of water? Our Bosch dishwasher was not draining.

See that pool of water? Our Bosch dishwasher was not draining.

After our built-in Bosch ran a cycle, the bottom of the dishwasher was still full of dirty, free-standing water.

Here's how it's supposed to work: There is a drain pump in the dishwasher that pushes the water out through a hose which typically runs from the dishwasher to either the sink's garbage disposal or the air gap. (Our air gap fits on the top of our sink. From there, another hose connects to the garbage disposal.)

If your dishwasher is not draining, something along this pathway is blocked or broken. Here are the troubleshooting steps to take.

How Do I Unblock My Dishwasher Drain?

  1. Check and clean the filter.
  2. Clean the air gap for clogs and damage.
  3. Check the drain hose.

Learn how to do each of these procedures, with video tutorials, below.

1. Check the Filter Inside the Dishwasher First

There is a screen in the bottom of the dishwasher that is supposed to block large debris from going into the drain hose, but sometimes pieces of food get through and clog the hose. The video below shows you how to check and clean the filter. If you find a big piece of food or glass, remove it and then run the rinse cycle to see if the dishwasher drains. If it still doesn't, move to the next step.

2. Check the Air Gap for Clogs

The most common problem that prevents a Bosch dishwasher from draining is small bits of food caught in the air gap. Luckily, this is very easy to fix.

  1. Locate your air gap. It's usually a little hood or cylinder at the back of your sink.
  2. Remove the cover. Most just unscrew or pop off by hand, but some have a small screw that holds it in place.
  3. The top of the air gap has a small piece that can be removed by depressing the small hooks. Remove the top and clean out anything clogged inside.

How it's supposed to work: Water is pumped from the dishwasher up through the air gap (that's the built-in plastic tube) and then usually down through a larger hose to the garbage disposal. The problem is that when the water hits the top of the air gap, small bits of food get stuck between the plastic lid and the built-in tube. This prevents the hose from working efficiently so the dishwasher doesn't completely drain. It's amazing what a huge problem a tiny bit of food can cause.

If you remove a bunch of debris, the problem is likely solved. Run the dishwasher on the rinse cycle and see if all the water is pumped out. If not, proceed to the next step.

What if I don't have an air gap?

Some units skip the air gap and drain directly into the garbage disposal by using what is called a high drain loop, which is an extra-long (at least 32" high) drain pipe that's fastened to the underside of the countertop. If you have a high drain loop, skip to step #3.

Pull the cover off your air gap and check for debris and tiny bits of food.

Pull the cover off your air gap and check for debris and tiny bits of food.

How to Unclog the Air Gap

3. Check for Clogs in the Drain Hose

To detach a drain hose from the air gap (or garbage disposal), you'll need...

  • a bucket
  • a screwdriver
  • pliers
  1. Using a screwdriver and the pliers, disconnect the drain hose that is attached to the air gap (or garbage disposal), drain the water, and check if the hose is blocked. You'll only be able to see the section of drain that's exposed under the sink.
  2. To see if the drain hose is blocked, run the dishwasher on the rinse cycle and hold the hose over the bucket. If the dishwasher doesn't drain, then the drain hose is blocked. You might try to use a plumbing snake or a hanger to push out the clog.
  3. If you can't find the clog in the section of drain under the sink, it's likely in the portion you can't see, directly behind the dishwasher. Most drain hoses run through a hole in the cabinet and the dishwasher may need to be pulled fully out for closer inspection. Before you pull it out, you'll need to unscrew the two L brackets that connect the top of the dishwasher to the underside of the counter. You may also need to adjust the height of the dishwasher by screwing its feet down lower to give you clearance at the top. If this is too difficult, it might be time to call a plumber.
This is an air gap that has been disconnected from the drain hose and the garbage disposal.

This is an air gap that has been disconnected from the drain hose and the garbage disposal.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: What does a Bosch e23 code mean?

Answer: An e23 error on a Bosch dishwasher is an electrical problem with the drain pump. It may require replacing the drain pump.

Question: Why would clean water gather at the bottom of a dishwasher if it's not run every day?

Answer: It’s possible that the drain hose bypasses an air gap and connects directly to the garbage disposal. Without an air gap water from the sink can flow back to the dishwasher so that you might have sink water flowing back in.

Question: Why would water be coming out of the air gap of my Bosch dishwasher?

Answer: There are a few possibilities. Air gaps are intended to prevent water from running back through the hose. So, two primary possibilities are there is a blockage or kink in the hose or a clog in the air gap. Another, but rather unlikely cause is the air gap is below the water causing a siphon of sorts. Take the air gap apart and check for small chunks like a piece of carrot. This is likely the culprit.

Question: I have a Bosch dishwasher that I've had for about 5 years. Tonight, it just stopped draining, and the washer started beeping. I checked the filter, which doesn't seem to be clogged. I check drain line and it didn't have much water in it. The washer will not rinse, or wash anything. Any suggestions?

Answer: Sometimes the beeping will be accompanied by an error code. Check for an error code. It sounds like you have done the basic troubleshooting. I'd try calling the appliance shop where you purchased it and see if you can talk to a repair person. They will often have additional troubleshooting tips or be able to give you an estimate of what the likely part will cost to replace it.

Question: What is the check valve on drain hose and what does it do?

Answer: A check valve is sometimes used in place of an air gap. Its purpose is to prevent water from flowing back in the opposite direction.

Question: Why will it not drain when the drain hose is clear?

Answer: There are a number of possibilities. The most common is a clogged airgap, clogged filter, and a bad pump. The first two are easy to remedy. A bad pump is more expensive. There is also the possibility the control board is bad. Look for error codes and call an appliance repair shop and they may be able to assist you.

Question: My 2017 Bosch dishwasher isn't draining properly. It shows E24 as the error code. I took out the filter and cleaned it, but there is a backlog of dirty water. Can you suggest what I might need to do?

Answer: The e24 error code may be associated with a few problems. For the DIY person, we suggest first making sure the check valve is clear. Next, check the hoses for kinks, and make sure the filters are clean. These are the basic steps. After this, the dishwasher may have an issue with the pump or control panel and will require pulling the dishwasher out. For most folks, this is where we recommend calling a repairman. For newer models, it's possible that it is still under warranty.

Question: My Bosch dishwasher keeps coming up with either "E18" or "E14" on the display. It did not empty and had a large pool of water in the bottom. Any suggestions?

Answer: These errors aren't associated with a draining issue, but rather a flow issue and a water level issue. Likely something is preventing enough water from flowing into the dishwasher.

Question: The water in my dishwasher sits below the filter, in the sump. Would vinegar and bi-carb remove any clogs or do I have pull out the machine and check the pipes manually?

Answer: A little water sitting below the filter is normal. It’s possible that there isn’t a check valve which can cause it or the way the older Bosch dishwashers work, they don’t completely dry, so a small amount of water can gather. That said, a rinse cycle with vinegar won’t hurt anything. The only downside is this small amount of water below the filter can start to smell if the dishwasher is used infrequently. If that’s the case, leave the dishwasher cracked open to dry and clean the filter. For a very small amount of water, below the filter, I wouldn’t pull the machine to check for clogs.

© 2010 Paul Edmondson

Comments

Karl Cole on January 03, 2020:

Got 3 times an error message on my Bosch 2017 model Ascenta dishwasher. I found the cause of the problem.. *Simply remove the kitchen sink drain plug to let evacuate the pressure from the pump! Otherwise a sensor will send an error message (E19 E35 and others) ''thinking'' that something is stocked at the pump.. which is not the case!!!

Matty on August 02, 2019:

I have a 5 year old silenceplus shxm66 model. Mice ended up chewing on the 300v wires to the heat pump coming from the main control. I was getting a E01 code and so decided to splice/repair the damaged wires. Now it’s just an E23 code. Is there a service diagram for testing resistance of the heat pump or control panel? Which component would have been most likely to be damaged if a mice had shorted the unit while it was operating? Thanks!

Colin Livingstone on May 13, 2019:

I have a SMS40T32UK dish washer. There is no easy way to access the water pump beyond the impeller.I think grit and fat deposits have bypassed the impeller and filters, yet this appears to be a sealed unit.Any ideas or fixes?

Sharon calkins on September 05, 2018:

Our Bosch silenceplus 50 dBA will not stop running even if we open the door. It just keeps running

dutch on August 26, 2018:

my dishwasher came up with code E24 ,,,CLEANED MY PUMP FILTER, CLEAN MY AIR GAP, still had stuff that I could not get to,,,,So I put a cup over the opened air gap and turned the rinse cycle and FLUSHED the line, washer now drains

CharlesDickens24 on August 21, 2018:

I had the draining problem. After trying a few things, I realized I replaced my garbage disposal but forgot to knock out the plug the drain hose for the dishwasher connects to. Problem solved.

JMills1 on April 11, 2018:

I have a Bosch Ascenta dishwasher that has worked well for about 3 years. Just after it was installed, the unit would drain completely and then fill with water from the drain about 1-1.5 hours later. The issue was repaired and there were no further problems. Now the issue has resurfaced again. The repair person cleaned the filter and hose and replaced the pump. This has not solved the problems. Any ideas? thank you in advance. It looks like this is the same issue JS is having.

Paul Edmondson (author) from Burlingame, CA on January 05, 2018:

Clean the filter, and check for any clogs. It's possible the motherboard or another part has an issue, that will need to be replaced.

JS on January 04, 2018:

My problem is the dishwasher completes its cycle, I turn it off and empty the dishwasher. This doesn't happen all the time. But, at some point, you could hear a short hum and what sounds like water coming through, and sure enough there's water at the bottom of the dishwasher. I have to run a short cycle to empty it. Any thoughts?

tom on October 01, 2017:

Alan,

I don't have an air gap either. There is a large plastic hose from the dishwasher to the disposal. The water pools in the drain below the filter and can smell quite bad if the washer is not used. HOw can I get the water to drain out. Thanks, Tom

Paul Edmondson (author) from Burlingame, CA on September 14, 2017:

@Alan if it's not completing the cycle, that's likely a different issue where the water in the bottom is a symptom.

Alan on September 13, 2017:

Paul, thanks for the info. It sounds like you're saying to Paul that it's normal for there to be a little pool of water in the very bottom sump between cycles? There are 1 or 2 cups in mine. I can't decide if that's normal or not.

Our Bosch gets stuck at various points in the mid rinse cycle and I'm trying to determine if it's a pump issue or not.

Paul Edmondson (author) from Burlingame, CA on September 10, 2017:

@Glenis, A little moisture is fine and if you clean the filter that should prevent it from smelling. You can also leave the door slightly cracked open and that will help as well. I don't think it impacts the dishwasher, but the newest models do have a different drying feature. I think it's more of a perception issue.

Glenis Rix on September 09, 2017:

A Bosch dishwasher is a fairly new addition to my kitchen and I had the same concerns as Jerry, so your response to him has set my mind at ease to some extent. But I'm concerned that if I'm away from home for an extended time (e.g. vacation) and therefore not using the machine regularly the stagnant water might breed bacteria and start to smell unpleasant. I'm wondering if incomplete drainage a design fault?

P.S. I take out the filter once each week to rinse it ( as per my instruction manual) and run a cycle with dishwasher cleaning fluid every few weeks.

Easy Fix for Bosch dishwasher error code E24 on September 09, 2017:

Thanks! When I took it off the trap the drain line had water in it up to the top. I went and got a garden hose and I flushed water back into the dishwasher (take off mesh filter first) and gunk did come out. I have a hand pump that small boat owners use to pull the water back out of the dishwasher. Runs great now. It was great to not have to take off any hoses or having to pull out the dishwasher. Thank You!

Canyon Jim on September 05, 2017:

I have a 2002 Bosch DW SHU5305UC/UC12 that quit draining. It works fine otherwise.

I have a high loop in my drain hose instead of an airgap.

My hoses allow air to pass in and out so I don't thibk they're clogged. The back flow tab ob the drain system did breakand was removed. Will that prevent the unit from pushing drain water to the outlet in my disposal? If it shouldn't, what else should I check? The motor runs and the pump pumps the water, it just won't go out of the pump into the disposal outlet. I woulsd apreciate input before I decide to junk it or spend more money. The flap isn't expensive, but if something else is invovled I'd like to determine those costs before spending time and money on the unit.

Paul Edmondson (author) from Burlingame, CA on August 30, 2017:

@Sue Sometimes the disposal can back up and water will come out of the air gap. It's also possible the line from the air gap to the disposal is blocked. First, run the disposal and try running the washer on a rinse cycle to see if that fixes the issue. Next, check the line from the air gap to the disposal. It's rare, but you can also try replacing or bypassing the air gap.

Sue rans on August 29, 2017:

I have a Bosch dishwasher and the air gap has dirty water after each wash I check and clean air gap but the same thing happens again. Any idea what could be the problem? Thanks

Paul Edmondson (author) from Burlingame, CA on August 22, 2017:

Sometimes they wear out and need to be replaced. If a dishwasher lasts over 10 years that's pretty good. It seems like the more electronic parts they add, the shorter they last. My previous Bosch lasted over 20 years I think.

Emma Foulkes on August 21, 2017:

I can't get my dishwasher to work. It started with dirty water in the bottom so I scooped it out, then cleaned the trap and filters, then checked the hose under the sink and I don't have an air trap. I've tried resetting it too but nothing is working. I've no idea what else to do!

Paul Edmondson (author) from Burlingame, CA on August 18, 2017:

@Holly disconnect the hose from the sink and run the rinse cycle with the hose in a bucket. If there isn't water, try a hanger to unclog it before removing the hose since that requires pulling the dishwasher out.

Holly on August 17, 2017:

Bosch dishwasher not draining. I have already checked the filter and removed the screw to make sure that the propeller is moving. And replaced this cover. I don't have an air gap on the countertop. Should I remove and check hose where it attaches in under the sink? Any help would be appreciated

Jerry Hunter on August 16, 2017:

Thanks for your quick response Paul. This alleviates my worries regarding the dishwasher draining properly. First time on this site but I'm book marking it in case I have further problems. Thanks so much for helping us "Dishwasher Challenged" people and saving us those dreaded service calls.

Paul Edmondson (author) from Burlingame, CA on August 16, 2017:

@jerry as long as there isn't any water in the pan, it should be fine. A small amount of water inside where the filter fits is normal. If it's pooling in the pan, then there is an issue. Also remember Bosch dishwashers can have moisture after the cycle completes - that's normal as well. However new Bosch Dishwashers have a new "dry" feature.

Jerry Hunter on August 16, 2017:

When our Bosch dishwasher Mod. SHUY3C02US finishes a wash I still find a small amount of water when I remove the filter. Is this normal or is it not completely draining? Thanks in advance.

Roy Schmoll on July 22, 2017:

Thanks Paul. Air-Gap - eh. Solved my issue.

Paul Edmondson (author) from Burlingame, CA on July 13, 2017:

Martha, glad it helped. If you have a newer Bosch and a garbage disposal, I'd consider rerouting the line and skipping the air gap. It's not really necessary. I just put in a new dishwasher and decided to do this. It's works great.

Martha on July 13, 2017:

Thanks so much, we've had 2 repairmen come out, and neither even checked the air gap! I was able to unclog it in 5 minutes thanks to your post. Not only did it stop the water from pooling, but my dishes are much cleaner.

zen on April 25, 2017:

i have a bosch dish washer its just taking the water and after filling its drain out ..may i know what is the problem .

Paul Edmondson (author) from Burlingame, CA on April 15, 2017:

I had a new Bosch installed and my wife was complaining it wouldn't drain. The first check was the air gap and sure enough, a tiny bit of food was stuck in it. It's a bit surprising how such a small amount of food can cause a clog. The good news is it's super easy to clear.

bobbrewer on April 15, 2017:

Thanks Paul, your post is still saving people money. such a simple fix.

Jeff on March 30, 2017:

Awesome, the air gap was clogged on mine, unclogged and it works - thank you!!

J925 on January 18, 2017:

Great tips! Thank you so much! I have been wondering why my dishwasher does not drain completely in the past 3 weeks. The air gap was clogged!

Paul Edmondson (author) from Burlingame, CA on October 25, 2016:

Jesse, I'm glad it worked well!

Jesse S on October 25, 2016:

Hey Paul,

Thanks for the info - worked great, saved me time & $$$. Tried option one (dw drain filter), which turned out not to be the problem. It was option 2, a clog in the airgap filter - nasty: salmon bones and other gunk! It was such an easy fix. Love not calling repair men. Feeling the DIY love bro!

Coincidently, I graduated from Cal Poly Pomona in 1970 with a degree in Management Information Systems - the early days of the computer age - never a dull moment.

Paul Edmondson (author) from Burlingame, CA on October 24, 2016:

I guess it's possible that the air gap is built in. Look up the model to see or call the appliance store and ask. It could have been installed incorrectly. The air gap is what prevents water from back washing into the dishwasher. It's possible the lack of an air gap is the problem.

Kristina on October 14, 2016:

What if you don't have an airgap? Have a brand new Bosch with the line running to the garbage disposal and it always has a few inches of standing water, which winds up smelling wretched between cycles.

Paul Edmondson (author) from Burlingame, CA on September 28, 2016:

@krista I always love to hear that this helps people fix it themselves. Thank you!

Krista on September 28, 2016:

Thank you so much - it was clogged air gap, and you just saved me $100 trip fee.

Ash on August 14, 2016:

You Rock! Thanks! I was on the last step and sure enough round the clog

Jodi on May 06, 2016:

it worked!!! thanks a million!

Jennifer on December 05, 2014:

Just cleared the air gap, carrots! Thank you! No more standing water.

Ralph on November 17, 2014:

Thank you for the great advice. I wish I had found your post earlier. I just finished running the dishwasher and there is no water left in the bottom. Thank again.

Celine on April 26, 2014:

I have the suds problem with my bosch dishwasher. Have had three different repair companys look at it. They all try to blame me . Getting a fourth repair man to try to fix it. Ladies, look in your dishwasher as soon as it finishes the cycle to see the suds. Or they go away after a short time.

Paul Edmondson (author) from Burlingame, CA on July 30, 2012:

Hopefully this is a bit more clear on how to remove the clog. Let me know if the instructions aren't clear.

Davidrwells on July 16, 2012:

I had same problem with my dishwasher as well but I called a plumber and he charged me heftily for a minor repair like that. At that time I didn't know I could do it myself but thanks to you I won't be spending my hard earned money on plumbers again.

jdh on June 02, 2012:

Amazing - this took care of my problem and just in time to avoid the repair man... Took me 45 min and saved me some time, trouble, and money bringing in a repair man.

darlenebb on April 03, 2012:

Great comments and helpful I am off to pursue fixing mine. I have water at the base of it and od not want expensive repair costs.

Melanie on November 15, 2011:

Great post. I used my steam vacuum cleaner to suck the water out of the dishwasher and then to suck water out of the drain hose. A bunch of pumpkin seeds came out. I did not put any pumpkin seeds into my dishwasher. They must have come from my garbage disposal. It's always a good idea to run the disposal before running the dishwasher. I do not have an air gap, most likely because my dishwasher was installed by some folks who are less than professional -- my dad gave me the dishwasher as a gift and used his people to install it, not professionals, such as you would get if you bought directly from Lowe's or Sears. Anyhow, these folks have done other jobs at my house, and their lack of knowledge regarding codes is astounding. They "repaired" a backflow preventer on my sprinkler system by installing a cheapo non-backflow preventer connector. Guess what? I soon had "air hammer," loud knocking in my walls. When I insisted that they do the job over with an backflow preventer that I purchased, the knocking went away. They also installed a microwave too close to the stovetop, so they had to redo it, and now I have two huge holes in the tile underneath my microwave. Beggars can't be choosers, and all of this was my dad's gifts to me, but I'd rather not have my house burn down due to code violations on a microwave or poison my family with backflow from my yard entering my drinking water supply. And now this! Yikes. I guess I need to install an air gap myself, or always remember to run the garbage disposal before running the dishwasher. Thanks for walking me through this!

DM on October 30, 2011:

Great post. It saved me a call to a repair man.

Dave P on October 24, 2011:

Just cleaned ours out and found some pumpkin seeds! Thanks for the helpful post!

plumbing on April 18, 2011:

Above all method of unclogging the drainage, removing the blockage physically is the most effective one. It is a long term solution for clogged drainage that homeowners should try at home to avoid spending bucks of money.

br14nwll on March 10, 2011:

Good Job, Paul! It is best to try to troubleshoot the problem first before calling a repairman.

sheila b. on August 25, 2010:

I once peeled carrots in the sink and then removed all but the tinyist little bits. Those got washed down the drain. And clogged it. Love carrots, but handle with care! And I'm impressed with your skill. First, you have to know what you're looking at, and what it does. Way beyond me!

GojiJuiceGoodness from Roanoke, Virginia on August 25, 2010:

Very Good info! I've never had this problem, but it's likely to happen sooner or later. :)

John B Badd from Saint Louis, MO on August 24, 2010:

These are some great tips.

Paradise7 from Upstate New York on August 24, 2010:

Good hub, I had a dishwasher with the same problem. We kept having to call the repairman, because neither of us knew how to fix it. Finally, we just resumed doing dishes by hand.

des donnelly from NYC.... on August 24, 2010:

this reminds me of Billy Connolly, the Scottish comedian, where he talks about vomit and asks how come it always contains carrots... even if you have not eaten any...

OMG, they are like Triffids, they are attacking dishwashers... ;-)

abrarr from USA on August 24, 2010:

that was a good hub regarding dishwasher problems and their maintanence.

2patricias from Sussex by the Sea on August 24, 2010:

Prevention is better than cure: scrape the plates before putting them in. However, it can be beyond difficult to train all members of the family to do so.

Congrats on fixing this yourself.

Ethel Smith from Kingston-Upon-Hull on August 24, 2010:

Well done you. These jobs often turn into huge expensive ones

Psalmist4M from the Shelter of His Wings on August 24, 2010:

Great information. It helps to have the information from someone who has experienced it first hand. Even the responses & comments are helpful advice and appreciated. Thanks for sharing.

Hello, hello, from London, UK on August 24, 2010:

To avoid all this rinse you dishes before you put them into the dishwasher. Thank you for pointing our the trouble and how to deal with it.

Lori J Latimer from Central Oregon on August 23, 2010:

Thank you for letting us know the problems with draining in a dishwasher.

gredmondson from San Francisco, California on August 23, 2010:

Some plumbing codes insist on air gaps, the purpose of which is to prevent water from the drain, or garbage disposal in Paul' case, from back flowing into the dishwasher. There are other devices besides air gaps that perform the same function. One of the reasons air gaps get clogged is that the filter screen will not be secured properly in the bottom of the dishwasher.