Whirlpool Dishwasher Error Code F18 — What It Means & How to Fix It

What Does This Error Mean?

The F18 error on your Whirlpool dishwasher means the machine tried to drain water but the water level did not drop within the expected time. The drain pump runs during this phase, and if the water is still present after the timeout, F18 is triggered. This usually means the drain path is blocked or the pump has failed.

Affected Models

Whirlpool WDF series
Whirlpool WDT series
Whirlpool 6th Sense series
Most Whirlpool dishwashers

Common Causes

The dishwasher filter is clogged with food debris and is blocking drainage
The drain hose is kinked or has a blockage preventing water from leaving
The drain hose connects to a garbage disposal that has not been knocked out — a common installation issue
The drain pump has failed and is not running or not generating enough flow
The air gap (if installed) is clogged with debris

How to Fix It

Remove the bottom rack. Locate the cylindrical filter assembly at the bottom of the dishwasher tub. Twist it counter-clockwise and lift it out.

A clogged filter is the most common cause of F18. Clean it thoroughly under running water with a brush.
While the filter is out, check inside the filter housing for any debris — broken glass, food scraps, or labels from dishes.

Even one small piece of debris can block the drain path enough to trigger F18.
Check the drain hose at the back of the machine and under the sink. Look for kinks, sharp bends, or blockages.

The hose should have a high loop under the sink (or connect to an air gap) to prevent backflow.
If your dishwasher drains into a garbage disposal, check that the disposal knockout plug has been removed. If the disposal was recently installed, this plug is often left in.

A knock-out plug left inside a new garbage disposal is one of the most common dishwasher drain problems after installation.
If the filter and hose are clear and F18 persists, listen during the drain phase. If you hear no pump noise, the drain pump has likely failed.

Drain pump replacement requires a technician who can access the pump from under the machine.

When to Call a Professional

If cleaning the filter and checking the drain hose does not fix F18, the drain pump likely needs replacement. Drain pump replacement typically costs $120–$220 at a repair shop. This repair requires accessing the underside of the dishwasher.

Frequently Asked Questions

How do I clean a Whirlpool dishwasher filter?

Pull out the bottom rack. Twist the cylindrical filter counter-clockwise and lift it out. Separate the flat mesh screen below it. Rinse both pieces under running water and scrub with a soft brush. Reinstall by placing the mesh screen first, then inserting the cylinder and twisting clockwise to lock.

How often should I clean my dishwasher filter?

At minimum, clean it once a month. If you run the dishwasher daily or frequently wash heavily soiled items, clean it every 1–2 weeks. A clean filter also improves washing performance — dirty filters are a major cause of cloudy dishes.

Is there water standing in the bottom of the dishwasher with F18?

Yes — if the drain failed mid-cycle, there will likely be standing water in the tub. You can manually remove this with a towel or wet/dry vacuum before attempting to fix the drain issue. Do not leave standing water in the machine for extended periods as it can develop odors and mold.