The dishwasher constantly drains water.

Instead of washing dishes, the dishwasher constantly fills and drains water—a problem that often leads users to call service centers. What could be wrong, and why is the machine no longer working properly? We think it's best to troubleshoot this yourself before calling a specialist. We're here to help.

Signs and causes of malfunction

A Bosch dishwasher that constantly drains is a common problem. Besides the humming sound of the constantly running motor, there are several other typical signs of a malfunction:

• an error code appears on the dishwasher display;
• the dishwasher does not respond when keys are pressed;
• nothing happens after rebooting the machine by turning it off and on again;
• water is constantly being poured in and drained out;
• the sound of water and the pump operating can be heard.

Fixing the leak

The most common cause of a Bosch dishwasher constantly draining is the activation of the Aquastop system. This occurs when water enters the dishwasher's tray, and the pump attempts to pump it out. When this problem occurs, the E15 error message appears on the Bosch dishwasher's display. If you listen closely, you'll hear that the dishwasher isn't filling with water.

To fix this problem, drain the water from the water pan. Also, make sure there's no water in the Aqua Stop sensor. On some Bosch models, this sensor is located on the right side of the machine, as shown in the photo. To get the water out of the sensor, experts recommend tilting the dishwasher at about 45 degrees.⁰. After this, you can try running the dishwasher again. Also, tilting the dishwasher can help if the Aqua Stop sensor is stuck in the "water" position.

Please note: In dishwashers with a mechanical Aqua Stop rather than an electric one, the entire hose must be replaced when the system is triggered.

One of the reasons the Aqua Stop system may be triggered is a crack in the water tank or reservoir. This is extremely rare, and self-diagnosis may require complete disassembly of the dishwasher. Even if you find such a crack yourself, replacing the part will require professional help, which is inconvenient to do at home.

Replacing the intake valve and pressure switch

When a Bosch dishwasher fills with water and then immediately drains, the likely cause is a faulty water inlet valve. When a wash cycle is initiated, the valve receives a signal to open, but when the signal to close is received, it fails to close, remaining open. As a result, the dishwasher continues to fill with water, causing an overflow. Once a certain water level is reached, the pump activates and begins draining the water. The process is getting stuck in a loop and the problem needs to be resolved urgently.

• You need to immediately turn off the water supply tap.
• Then wait a while until the pump stops working; if it continues to hum, then disconnect the machine from the electrical network.
• Now pull the dishwasher out so you can easily access the inlet hose connection. In Bosch dishwashers, the hose connects at the rear, but some dishwashers have the inlet hose connection located under the front lower panel.
• Disconnect the water supply hose from the machine. Immediately behind it is a mesh water filter, and behind this mesh is the inlet valve.
• Using a multimeter, you need to check the functionality of the electrical part of the valve. The multimeter probes are pressed against the valve contacts and the value is checked, which should normally be between 500 and 1500 Ohms. Otherwise, the valve is faulty and needs to be replaced with a new one.
  
• If the electrical part of the inlet valve is working properly, you need to check the mechanical part. This is much more difficult. One way is to open the machine door several times while the water is filling. If water continues to fill, the valve is faulty or clogged and needs to be replaced.

After replacing the faulty valve, the constant water drain issue may be resolved. Run a test wash and check the machine's functionality.

If the problem with the dishwasher filling and draining water isn't the valve, it's worth checking the pressure switch. It controls the water level in the machine. If the signal indicating the reached water level isn't sent to the control board, water will constantly fill or drain. Detailed instructions for checking this part are in the article. Replacing the pressure switch in a dishwasher.

Control board faulty

One of the reasons for this in some Bosch dishwasher models or other brands may be a faulty control board. To be more precise, the pump's thyristor fails. As a result, a situation may arise where the pump constantly drains water, even when there is no water, but the user hears the pump running.

The triac on the control board can be resoldered. However, this work requires someone with electronics knowledge, the ability to read schematics for various dishwasher models, and the ability to use a soldering iron. Therefore, this type of work is usually entrusted to a professional.

So, there could be several reasons why your dishwasher is constantly draining. In some cases, you can fix the problem yourself, as long as you have at least a basic understanding of your dishwasher. Happy repairing!

   

1 reader comment

1. September 24, 2020 at 2:03 PM

   Sportiv:

   Technician, please advise me on my Bosch SMS41D08EU dishwasher. The faucet and snowflake lights are flashing, water is constantly filling (the electronics can't stop the flow), and when the water level is reached, the pump drains continuously. The cycle continues in a loop—constant filling, then draining when the water level is reached. The water flow doesn't stop when the door is opened. The inside of the machine is completely dry, and there are no leaks. The float is in place and not stuck.
   What could be the problem?! What should I check? Thank you so much in advance!!

   Answer