Dishwasher Not Cleaning Dishes? 8 Reasons and What to Do

Opening your dishwasher to find food still stuck on plates is frustrating, especially when you just ran a full cycle. Before assuming the machine is broken, there are several common causes that range from simple user fixes to parts that need replacing. Here is what we check during a dishwasher service call, in the order we check it.

1. Clogged Spray Arms

The small holes in the upper and lower spray arms can clog with food particles, mineral deposits, and grease. When these holes are blocked, water cannot reach your dishes effectively.

Fix: Remove the spray arms (they typically twist off or unclip), soak them in warm vinegar water for 30 minutes, and use a toothpick to clear each hole. This is the most overlooked maintenance task and solves about 25% of "not cleaning" complaints.

2. Dirty or Clogged Filter

Most modern dishwashers have a removable filter at the bottom of the tub. If this filter is packed with food debris, the wash water recirculates dirty water over your dishes instead of clean water.

Fix: Remove the filter (twist counterclockwise), rinse under running water, scrub with a soft brush, and replace. Clean this filter every 2–4 weeks for best performance.

3. Wrong Detergent or Too Much Detergent

Using the wrong detergent or too much of it causes excess suds that actually reduce cleaning power. Pods or tablets generally outperform liquid and powder for consistent dosing.

Fix: Switch to a high-quality dishwasher pod. Never use dish soap (hand-washing liquid) in a dishwasher — it creates a suds overflow.

4. Low Water Temperature

Dishwashers need water at 120°F to dissolve grease and detergent effectively. If your home water heater is set too low or the dishwasher is far from the water heater, the incoming water may be lukewarm.

Fix: Run the kitchen faucet on hot until it reaches full temperature before starting the dishwasher. Check your water heater setting — it should be at 120°F.

5. Faulty Water Inlet Valve

If the dishwasher is not filling with enough water, it cannot clean effectively. The water inlet valve controls how much water enters the tub. A failing valve may only partially open, resulting in low water levels.

Repair cost: $90–$160 for inlet valve replacement.

6. Worn Wash Motor or Pump

The wash motor drives water through the spray arms at pressure. If the motor is weak or the pump impeller is damaged, water pressure drops and dishes come out dirty.

Signs: Low water noise during the wash cycle compared to when the dishwasher was new. Reduced spray arm rotation.

Repair cost: $150–$280 for wash motor replacement.

7. Broken Soap Dispenser

If the detergent dispenser door does not open during the wash cycle, the detergent sits undissolved in the closed compartment. Check if the dispenser spring or latch is broken. Also check that tall items on the bottom rack are not blocking the dispenser door from opening.

Repair cost: $50–$100 for dispenser mechanism replacement.

8. Loading Issues

Overloading or improper loading blocks water and spray from reaching all surfaces. Nesting bowls together, placing large items in front of the spray arm path, or blocking the detergent dispenser are common loading mistakes.

Fix: Leave space between items. Face dirty surfaces toward the spray arms. Do not block the center spray tower or detergent dispenser.

Maintenance Schedule for Clean Dishes

When to Call for Repair

If cleaning the filter, spray arms, and adjusting your loading and detergent does not improve results, the issue is likely mechanical: a weak pump, failing inlet valve, or malfunctioning control board. These require a technician with diagnostic tools and replacement parts.