Dishwasher Won't Drain? Diagnose and Repair it Yourself!

If your dishwasher is not functioning optimally, the problem can most often be traced back to a blockage in the drain or drain pump. Work through the following steps to quickly diagnose and repair your machine. A professional can help you as well.

Troubleshooting the problem

If your dishwasher is showing signs of inadequate drainage, this is most often the result of a foreign object which has made its way into or beyond the filter to the drain pump, creating a blockage. Closely examine the filter at the bottom of your machine for debris: small items of cutlery, plastics or broken glass can often get caught here and lead to problems with drainage. Remove any debris that you find. If any debris has made its way past the filter and into the drain pump, you will be able to confirm this based on the sound of your machine as it goes through its cycle. Debris interferes with the blades of the drain pump's impeller, creating an uneven or laboured sound as it spins. If you suspect that there is a blockage, you will need to remove this to restore proper function to your machine.

Removing the blockage: Step 1

First, turn off the water supply to your machine and disconnect the water inlet hose. This will allow you to lay the dishwasher flat on its back and provide access to the bottom of your machine. Modern dishwashers are fitted with a removable panel on the base which guards the internal components. Remove this base panel to access the drain pump. Consult your product manual to ascertain the location and appearance of the pump. An anti-flood switch will be present on or near the base panel: unscrew this if it is attached to the panel itself to allow you access to the inside of your machine.

Step 2: Removing the drain pump

The drain pump will be removable for cleaning or replacement. Remove the connections supplying power to the pump. Note: Taking a photograph of the internals of your machine before removing any components will help you to replace components properly on reassembly. Unscrew and remove the drain pump for closer inspection.

Step 3: Remove debris and replace the pump  

Remove any visible debris from the drain pump and check that the impeller is able to rotate freely. Be sure to also examine inside the pump's housing for debris. Once the blockage is removed, reattach the pump and your machine should once again be functioning optimally. If there is no visible debris in the pump or housing, the drain pump itself may be faulty. Using an ohmmeter, check the resistance across the pump's terminals: you should expect a reading of around 180 to 220 Ohms. If your reading is outside of this range, invest in a new pump and fit this in place of the old part. You should find that your dishwasher will now drain properly. If the problem persists, call a professional repair service for a more thorough inspection of your machine. Good luck!