Troubleshooting a Dishwasher That Won’t Drain: Is It the Drain Pump?

Troubleshooting a Dishwasher That Won’t Drain: Is It the Drain Pump?

A dishwasher that won’t drain can leave you with a sink full of dirty water and dishes that aren’t properly cleaned. One of the most common culprits is the drain pump, but before replacing it, let’s go through some troubleshooting steps to confirm whether it’s the real issue.

Common Causes of a Dishwasher Not Draining

Before assuming the drain pump is faulty, consider these other common reasons why your dishwasher might not be draining:

1. Clogged Drain Hose

Food particles, grease, or even small objects can block the drain hose, preventing proper drainage. Try disconnecting the hose and checking for obstructions.

2. Blocked Air Gap or Garbage Disposal Connection

If your dishwasher drains through an air gap or into a garbage disposal, a clog in either component can stop water from flowing out. Cleaning the air gap or ensuring the disposal inlet is clear may resolve the issue.

3. Faulty Drain Solenoid

Some dishwashers use a drain solenoid to open the drain valve. If this part fails, the valve may stay closed, preventing drainage. Inspecting and testing the solenoid with a multimeter can determine if it's faulty.

4. Clogged Filter or Sump Area

Many dishwashers have a removable filter or sump area that collects debris. If this is clogged, water can’t flow to the drain pump. Cleaning the filter regularly helps prevent blockages.

Is the Drain Pump the Problem?

If you’ve ruled out the issues above, your drain pump could be at fault. The drain pump forces water out of the dishwasher and into the drain hose. Here’s how to check if it’s the problem:

Signs of a Faulty Drain Pump

  • The dishwasher hums but doesn’t drain.
  • Water remains at the bottom after a cycle.
  • You hear grinding or unusual noises from the pump.
  • There are no visible blockages, but the pump isn’t moving water.

How to Test the Drain Pump

  1. Disconnect Power: Always unplug the dishwasher or turn off the breaker before working on it.
  2. Locate the Pump: The drain pump is usually found beneath the dishwasher, near the filter.
  3. Check for Obstructions: Remove any debris blocking the pump impeller.
  4. Test with a Multimeter: Using a multimeter, check for continuity in the pump motor. If there’s no continuity, the pump needs replacement.

Why Is My Dishwasher Not Draining?

A dishwasher that won’t drain could have a clogged drain hose, air gap, or filter, but a faulty drain pump might also be the culprit.

How to Fix a Dishwasher That Won’t Drain

  1. Check the Drain Hose – Remove blockages by running water through it.
  2. Clean the Air Gap or Garbage Disposal – Ensure water can flow freely.
  3. Inspect the Drain Solenoid – Test it with a multimeter for continuity.
  4. Remove Debris from the Filter – A clogged sump prevents proper drainage.
  5. Test the Drain Pump – Listen for a humming sound or check with a multimeter.

How Do I Know If My Drain Pump Is Bad?

  • The dishwasher hums but doesn’t drain.
  • Water remains in the bottom of the tub.
  • The pump makes grinding or unusual noises.

Replacing the Drain Pump

If the drain pump is defective, replacing it is often the best solution. Make sure to purchase a compatible replacement from a trusted parts supplier like PRS Parts Inc. in Honolulu.

Need a New Drain Pump? We Can Help!

At PRS Parts Inc., we carry high-quality dishwasher replacement parts to get your appliance working like new. Visit us or call to find the right part for your repair.

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