LG Dishwasher Not Draining: Causes and DIY Fix Guide

BySir Fix A Lot

If your LG dishwasher won’t drain, the most common culprit is a blocked drain filter or a kinked drain hose—both fixable in under 15 minutes with basic tools. A stuck drain pump or a failed impeller is less common but still DIY-able. Start with the easiest checks first; you may save a service call.

First, Check These Three Things

Before opening the pump or removing the dishwasher, rule out the simplest causes. These three checks catch roughly 80% of LG drain problems.

  • Look at the drain filter basket – Remove the bottom rack and twist the cylindrical filter counterclockwise. Lift it out. Food debris, broken glass, or a stray bottle cap often blocks the screen. Rinse under running water and reinstall.
  • Inspect the drain hose – Pull the dishwasher out enough to see the hose running from the unit to the sink drain or garbage disposal. Look for sharp kinks, pinched sections, or a sagging loop that traps water. Straighten any bends.
  • Check the air gap – If your setup has a small chrome cylinder on the countertop (air gap), pop the cap off and clean out any debris. A clogged air gap will prevent drainage even if the pump works fine.

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What You See After the First Check Changes Your Next Move

If you clear the filter or hose and water begins to drain, you’re done—run a rinse cycle and verify the tub empties completely. But if you clean everything and the dishwasher still holds water, the problem isn’t a simple blockage. That’s your signal to move to the sump area and check the check valve before touching the pump. A stuck check valve mimics a failed pump, and replacing the pump when the valve is the real issue wastes time and money.

Common Causes of Drain Failure (and Why They Happen)

LG dishwashers use a sensor-driven drain cycle that relies on a clear water path. When drainage stops, it’s almost always a mechanical blockage, not an electronics failure. Here’s what typically goes wrong:

Clogged Drain Filter or Sump Area

The fine-mesh filter catches large food particles. Over time, bits of eggshell, rice, or grease build up and restrict water flow. The dishwasher may still run but leaves an inch of water at the bottom.

Kinked or Blocked Drain Hose

If the hose is wedged behind the dishwasher or crushed under the sink, water can’t exit. A kink acts like a pinch valve. During installation, the hose often gets pushed too far back.

Failed Drain Pump (Impeller or Motor)

The drain pump has a plastic impeller that spins to push water out. Hard water deposits or a small piece of metal can snap the impeller blades. The motor runs, but the impeller doesn’t spin—so you hear the pump hum but no drainage. This is the counter-intuitive angle most guides miss: the pump may sound normal but still be stripped internally.

Check Valve Stuck Closed

A small flap inside the sump prevents water from flowing back into the dishwasher. If a grain of rice or a piece of plastic jams it closed, the pump can’t push water past it. The pump will run, but water stays in the tub.

Step-by-Step DIY Fix: From Filter to Pump

If the quick checks didn’t clear the problem, move through these steps in order. Each step eliminates a possible cause without wasting time on unnecessary disassembly.

Step 1: Deep Clean the Filter and Sump

1. Remove the bottom rack and spray arm.

2. Twist out the cylindrical filter and the flat mesh screen beneath it.

3. Use a small brush (old toothbrush works) to scrub the sump opening where the filter sits. Look for a small rubber flapper (check valve) – push it gently to make sure it moves freely.

4. Reinstall everything and run a rinse cycle.

Step 2: Clear the Drain Hose

1. Disconnect the hose from the sink drain or garbage disposal. Have a bucket ready.

2. Blow into the hose or use a wet/dry vacuum on the end to dislodge any blockage.

3. If the hose is damaged or has a permanent kink, replace it with a standard ⅝-inch dishwasher drain hose (about $8–12).

Step 3: Test the Drain Pump

If water still won’t drain, the pump likely needs attention.

  • Remove the lower kickplate and locate the drain pump (usually a small black cylinder with two wires).
  • Spin the pump impeller by hand through the sump opening (use a flashlight). If it doesn’t spin freely, the impeller is broken.
  • If the impeller spins but the pump doesn’t run, test the motor with a multimeter. A reading of 0 ohms or infinite indicates a short or open circuit.
  • Replace the pump assembly if needed. A genuine LG drain pump costs around $40–60 and requires removing the pump mounting screws and swapping the hose clamps.

How to Verify the Fix Actually Worked

After completing any of the steps above, run a short rinse cycle (no detergent needed). When the cycle finishes, open the door and check the bottom of the tub. Normal behavior is less than a tablespoon of water in the filter well—any more means the fix didn’t fully resolve the blockage. If you replaced the pump, also listen for a smooth whirring sound during the drain phase; a grinding or clicking noise indicates the new pump may be misaligned or the impeller is catching debris.

Decision Aid: Quick Triage Checklist

Use this before you start any disassembly:

  • [ ] Filter basket is clean and free of debris
  • [ ] Drain hose is not kinked, pinched, or sagging
  • [ ] Air gap (if present) is clear
  • [ ] Check valve in sump moves freely when pushed
  • [ ] Pump impeller spins smoothly by hand
  • [ ] No error code displayed (write it down if present)
  • [ ] Water level is less than 1 inch after a failed cycle

If you checked all seven and water still won’t drain, move to the pump test.

When to Stop and Call a Pro

Escalate if:

  • You find a burned smell or see scorch marks on the pump wires.
  • The pump motor is seized and won’t spin at all.
  • You’ve replaced the pump and the hose but the dishwasher still doesn’t drain.
  • The control board shows repeated error codes like OE (drain error) or SE (motor error) after cleaning.

In those cases, the issue may be a faulty control board, a wiring harness break, or a failed drain pump relay. A technician can diagnose with a multimeter faster than you can replace parts blindly.

Preventive Maintenance to Avoid Future Drain Issues

  • Clean the drain filter every 30 cycles (or monthly if you run daily loads).
  • Run a hot-water rinse cycle once a week to flush grease buildup.
  • Scrape plates before loading; don’t use the dishwasher as a garbage can.
  • Check the drain hose annually for kinks; if you’ve had a recent repair or installation, inspect the hose routing.

A stuck drain is rarely a catastrophic failure. Most LG dishwasher drain problems are resolved by cleaning the filter or straightening the hose. If you’ve already tried those steps and still have standing water, check the pump impeller and check valve before scheduling a service visit. For a related issue where water remains but dishes aren’t clean, see our lg dishwasher not cleaning fix guide. If you’re dealing with water leaking from the unit, the lg dishwasher leaking fix page covers common leak points.

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