Bosch Dishwasher Not Draining but No Blockage: How to Fix It

The most common cause of a dishwasher not draining is a blockage somewhere in the drainage system. However, if you’ve already checked the filter, drain hose, and garbage disposal for blockages and found them free of obstructions, there are a few other issues that could potentially cause your Bosch dishwasher not to drain.

From a damaged pump to a faulty check valve, this article will explore all the reasons why a Bosch dishwasher may not be draining, aside from blockages. It will also offer troubleshooting tips to help you get your Bosch dishwasher working properly again.

Keep reading to learn how to fix a Bosch dishwasher that isn’t draining, even when there are no blockages.

Why your Bosch dishwasher isn’t draining despite no blockages

Here are the most likely causes and how to fix them.

An issue with the drain pump

The drain pump in a Bosch dishwasher is responsible for removing wastewater at the end of the wash cycle. It pumps the dirty water out through the drain hose and into the household drainage system.

An issue with the drain pump, such as damage to the impeller or a failed motor, can result in the dishwasher not draining.

How to fix the drain pump

It really depends on the severity of the problem, but often a faulty drain pump will need to be replaced rather than repaired. Follow these steps to fix various drain pump-related issues:

1. Shut off the power and water supply to your Bosch dishwasher.
2. Take out the lower rack, spray arm, and filter.
3. Manually remove any water that hasn’t drained from the base of the tub using a sponge and small container.
4. Access the impeller by removing the pump cover that’s located in the housing where the filter sits. The pump cover is a white plastic tab that pulls out, though sometimes it’s secured with a screw.
5. Inspect the impeller for damage, such as broken blades. Check that it spins freely and that no foreign objects are obstructing it.
6. Remove any pieces of plastic, glass, or other obstructions you find from the impeller. And if there are no other signs of damage, reassemble your dishwasher and test if it’s now draining.
7. If the impeller is damaged, you’ll need to replace the entire drain pump since the impeller can’t be repaired or replaced separately.
8. To access the drain pump, remove the lower access panel from the bottom front of the appliance. It will be secured with screws.
9. The drain pump will be located directly under the filter housing.
10. Inspect the drain pump for damage, such as cracks in its housing or visible leaks. Also, check the wires connected to it.
11. If damaged, remove the bad drain pump by disconnecting its wires and the drain hose. Have a container ready to catch any water that spills from the drain hose. Then, remove any screws securing the drain pump.
12. Install the new drain pump, ensuring the wires and drain hose are connected correctly. Then reassemble the dishwasher and test to see if it’s now draining.

An issue with the check valve

The check valve on a Bosch dishwasher is a one-way valve located near the drain pump. Its main purpose is to prevent wastewater from flowing back into the dishwasher after it’s been drained. This ensures dirty water doesn’t re-enter the tub and contaminate clean dishes.

If the check valve is faulty, water may flow back into the tub, making it seem like it’s not draining.

How to fix the check valve

Follow these steps to fix the check valve:

1. Shut off the power and water supply to your Bosch dishwasher.
2. Take out the lower rack, spray arm, and filter Then remove the pump cover (located inside the filter housing).
3. Manually remove any standing water from the base of the tub with a sponge or small container.
4. Locate the check valve, a small rubber flap beneath the pump cover. Remove it by pulling it out.
5. If it’s damaged or worn, replace it with a new one.
6. If it’s dirty, clean it and the area where it sits, then reinstall it.

The dishwasher isn’t level

Your Bosch dishwasher needs to be level to function optimally. If it’s not level, water can pool in areas of the tub and fail to drain. You can check whether it’s level by placing a spirit level on top of the appliance or by removing the lower rack and placing it in the interior.

How to level a Bosch dishwasher

To fix an unlevel Bosch dishwasher, follow these steps:

1. Remove the lower access panel, also called the kick plate, to access the leveling system.
2. Turn the screw on the rear leveling mechanism clockwise with a flat-head screwdriver to raise the back of the dishwasher or counterclockwise to lower it.
3. Turn the screws on the front feet clockwise with a flat-head screwdriver to raise them or counterclockwise to lower them.
4. Keep adjusting the legs until the spirit level shows that the appliance is level.

The garbage disposal’s knockout plug hasn’t been removed

The knockout plug is a small plastic plug that blocks the opening where the dishwasher drain hose would connect to the garbage disposal. Not everyone connects their garbage disposal to a dishwasher, so this plug prevents water from leaking through the unused connection.

However, if your dishwasher was recently installed and the installer forgot to remove the knockout plug, the dishwasher will not drain.

How to remove the knockout plug

You can remove the knockout plug from the garbage disposal by following these steps:

1. Turn off the power to the garbage disposal.
2. Disconnect the dishwasher’s drain hose from the garbage disposal.
3. Use a screwdriver and a hammer to gently knock out the plug in the opening of the garbage disposal.
4. Remove the knockout plug from within the garbage disposal.
5. Reconnect the dishwasher’s drain hose to the garbage disposal.