Bosch Dishwasher Drain Pump Test Explained (Troubleshooting!)

There’s nothing worse than a Bosch dishwasher that doesn’t drain, and sometimes the problem is with the drain pump. As such, it’s important to conduct a Bosch dishwasher drain pump test and fix the problem if any.  

A Bosch drain pump test allows you to know exactly what’s wrong, which should be the reason why the dishwasher is unable to drain in the first place. The test can help you to determine whether the motor is dead or if the impeller seal is bad. 

There are often two reasons why a Bosch dishwasher may fail to drain properly.

First, the unit may fail to drain properly because of clogging in the drain pump. The pump may also have kinks keeping water moving to the drainage.

And second, the problem might be with the drain motor, which, again, makes it difficult for the drain pump to drain water out of the dishwasher.

In this guide, I’ll address both issues, showing you exactly what to do, so you can get your unit draining properly after a wash cycle.

Let’s get started.

bosch dishwasher drain pump test

Bosch Dishwasher Troubleshooting Not Draining

Every dishwasher, from General Electronics and Whirlpool to Bosch and Frigidaire, includes a drain pump that expels water through a hose routed from the dishwasher to either the trash disposal in the sink or the air gap.

If the water from your dishwasher is not draining properly, there is likely a blockage or a break somewhere along this channel.

So if your Bosch dishwasher’s drain pump doesn’t seem to be working, you should: 

  • Clean the filter
  • Remove clogs from the air gap
  • Clean the drain hose

1. Clean the Filter

Your Bosch dishwasher has a screen in the bottom of the dishwasher that prevents debris from entering into the drain hose. However, there are instances when fragments of food manage to sneak past the screen and clog the drain hose.

If you discover a large piece of food or glass in the dishwasher, remove them before proceeding to the rinse cycle.

Then, check if the unit can drain properly. Otherwise, inspect the air gap if this solution doesn’t solve the problem.

2. Remove Clogs from the Air Gap

Here’s how the air gap in a Bosch dishwasher should work:

The drain pump pushes water from the dishwasher up via the air gap and then send it down to the waste disposal by a bigger hose.

The issue is that when the water reaches the top of the air gap, there is a potential for food particles of varying sizes trapped between the plastic lid and the built-in tube. This inhibits the hose from functioning as efficiently as it should, which results in the dishwasher not being able to drain.

To be clear, the presence of even the tiniest pieces of food in the air gap is by far the most prevalent cause of a Bosch dishwasher’s inability to drain properly.

  • Locate your air gap. It’s at the very rear of your sink, in the shape of a hood or a cylinder of some kind.
  • Take off the covering by simply unscrewing or popping it off by hand.
  • Take off the top, and clear away any debris that has accumulated within.

If you clear away a significant amount of the food particles, the issue should no longer exist, and your Bosch dishwasher should drain properly. Check to ensure that the dishwasher has sucked out all of the water by running it through the rinse cycle.  

3. Clean the Drain Hose

Here’s how you do it:

  • Disconnect the drain hose from the air gap and let the water to run out of the hose.
  • Check to see whether there are clogs blocking the drain hose from working
  •  Run the dishwasher through the rinse cycle while holding the drain hose over the bucket. This will allow you to determine whether the hose has clogs.  

If you cannot remove the contents of the dishwasher, the problem likely lies inside the pipe. You might try to get the blockage out of the drain by using a plumbing snake or a hanger.

If you are unable to locate the clog in the piece of the drain that is located beneath the sink, the obstruction is most likely located in the section right behind the dishwasher.

The majority of drain hoses pass through a hole in the cabinet, so you might have to remove the dishwasher to do a more thorough check.

  • Unscrewing the brackets that link the top of the dishwasher to the underside of the counter
  • It’s possible that you’ll also need to alter the height of the dishwasher by screwing its feet down lower so that you have more room at the top.

If there’s no problem with these three components, but your Bosch dishwasher won’t drain at the end of the cycle, then it’s highly likely that the drain pump may be having a problem.

How Do I Know My Bosch Dishwasher Drain Pump is Bad?

The last thing you want is a dishwasher that won’t drain. But as good as a Bosch model is, the drain pump just might go bad and demand a complete replacement.

But how do you know if the drain pump of your Bosch dishwasher is bad? Well, you will know that your Bosch dishwasher drain pump is bad because:  

1. The Dishwasher Doesn’t Drain at All

A malfunctioning drain pump causes your Bosch dishwasher to cease draining. The unit will stop and fail to remove water from the compartment and therefore unable to dispose it off to your home’s drainage system.

And even if the unit continued to wash your dishes with used water, they would end u much dirtier than before.

2. The Unit Takes Long to Drain

The purpose of a drain pump is to speed up the process of draining the dishwasher. So if your dishwasher’s drain pump is in good condition, it should take only a few minutes to for the appliance to drain completely.

If you notice that it takes longer than usual for your Bosch dishwasher to drain, it’s more than likely that the drain pump has gone bad.

3. There’s Standing Water After A Wash Cycle

There shouldn’t be water remaining in the dishwasher after a complete wash cycle. But should this be the case, there’s a high chance the drain pump is faulty.

4. Bosch Dishwasher Makes a Low Humming Sound

It’s also a good idea to pay attention any unusual noises that may indicate a problem with the appliance’s drainage.

For example, if you hear a low, constant buzzing noise from your Bosch dishwasher, then it’s highly likely that the drain pump has foreign objects lodged in it.

As you may recall, every Bosch dishwasher has an impeller within the drain pump that propels water down the pipe. If foreign objects from the dishwasher reaches the pump, the impeller will be unable to revolve, making it difficult for the machine to drain properly.

5. Water Seeps through the Floorboards

If the dishwasher drain pump isn’t working properly, the water might flow onto the floor. This is because water builds up within the dishwasher because the pump is unable to remove it down the drain line as intended.  

As the dishwasher fills up with water, some of it will leak out via the dishwasher’s holes and end up on your kitchen floor.

Where is the Drain Pump on a Bosch Dishwasher?

Bosch dishwasher’s drain pump is beneath the sprayer arm. This part circulates water throughout the dishwasher.

The pump features top and bottom impellers, which, if clogged with dirt, debris, or detergents, can cause the unit not to drain.

How to test Bosch Dishwasher Drain Pump with Multimeter

To test the dishwasher pump with a multimeter:

  • Remove the sprayer arm’s retaining cap.
  • Remove other components that cover the drain pump, including the spray arm, food disposer blade, upper impeller, screen, pump housing, bolt, O-ring, spacer plate, impeller hood, flat plate, and bottom impeller.
  • Touch the pump’s terminals with the probes of the multimeter in Rx1 mode.
AstroAI Multimeter

Keep in mind that what you’re doing here is to conduct a continuity test. The intent is to get a reading of zero or close to zero.

  • Test the ground connection by touching one of the probes to the housing’s bare metal while leaving the other probe on a terminal. Make sure this test doesn’t give any results.

If your test results differ from those listed above, you have a faulty drain pump that you’ll have to replace if your Bosch dishwasher must drain properly.

Bosch Dishwasher Drain Pump Replacement

Drain pumps are important components in Bosch dishwashers, but they tend to wear out over time. If you’ve tested your unit’s with a multimeter and noticed that it failed the continuity test, you should consider replacing it immediately.

Here’s how:

Remove the Old Drain Pump

To remove the old drain pump from the Bosch dishwasher:

  • Turn off the dishwasher’s power supply by unplugging it from the electrical outlet.
  • Use a small container and a sponge to empty excess water from the unit.
  • Pull the dishwasher away from the wall. If the hose is not long enough to allow you to move the dishwasher, disconnect the water supply.
  • Disassemble the dishwasher to access to the drain pump.
  • Remove the top panel and the side panels of the dishwasher.
  • Remove the kick strip from the bottom of the dishwasher. Some models have it secured with two screws while others have it held in place by a clip.
  • Unscrew the screws that secure the cover plate to the frame of the dishwasher to remove the cover plate.
  • Unplug the cables from the water detection sensor to access the drain pump
  • Turn the drain pump in a clockwise direction to detach it from its housing.
  • Remove the electrical plugs from the unit of the drain pump (you may need to unlock them to separate them).

Installing a New Drain Pump

Here’s how to install a new drain pump in you Bosch dishwasher:

dishwasher drain pump
  • Place the new drain pump into the housing, ensuring you position it “square” within the housing to prevent leaks, and slowly rotate it counterclockwise until it clicks into place.
  • Reconnect the wiring to the new drain pump, ensuring you securely fasten it in place.
  • Restart your dishwasher at the wall and initiate a brief rinse cycle. This allows you to verify that the new drain is functional and that there are no leaks. (Clonazepam)

If the dishwasher drain pump is functioning properly and there are no error messages on the control panel, you can begin to reassemble the appliance.

Frequently Asked Questions

1. Can I Force a Bosch Dishwasher to Drain?

You can try forcing your Bosch dishwasher to drain by resetting the unit. To do this, unplug the dishwasher from the power source, wait at least 5 minutes, and the reconnect it again.

2. What Can I Do If My Bosch Dishwasher Won’t Drain? 

Check if there are clogs in the air gap and the drainpipe and do a thorough cleaning. Also, inspect the drain pump by running a continuity test and do replacements if the test doesn’t return zero or close to zero results.


I hope this guide helps you to run a Bosch dishwasher drain pump test and fix the problems associated with the unit not draining properly.