Why is my Bosch dishwasher not cleaning properly?
Poor cleaning usually points to blocked spray arms, a faulty pump, or detergent issues. This guide helps you identify which component is failing.
Most likely causes
- 35% Blocked or clogged spray arms preventing water distribution to dishes.
- 25% Worn or faulty circulation pump not building sufficient water pressure.
- 20% Blocked filter basket trapping food and restricting water flow.
- 12% Insufficient or incorrect detergent type for your water hardness.
- 8% Failed heating element preventing hot water from reaching optimal temperature.
How to diagnose it
- 1
Check spray arm rotation
Remove the upper basket and spin both spray arms by hand. They should rotate freely without resistance. If stuck or grinding, they're blocked or bearing is worn.
💡 Look for white mineral deposits around the spray holes.
- 2
Inspect spray arm holes
Hold each spray arm up to light and look through every hole. Use a toothpick or needle to clear any food debris or mineral buildup. Push water through with your finger to test flow.
💡 Soak arms in white vinegar for 30 minutes if heavily calcified.
- 3
Empty and rinse filter basket
Remove the cylindrical filter from the base and empty any trapped food. Rinse under running water and check the fine mesh isn't torn. Reinstall and run a short cycle.
💡 This is the most common cause—check it first.
- 4
Test detergent dosage
Check you're using the correct amount for your water hardness setting. Use only dishwasher detergent, not washing-up liquid. Switch to a quality brand if using budget products.
💡 Underfilled detergent dispensers are a frequent culprit.
- 5
Run empty hot wash
Empty the dishwasher completely and run a 70°C cycle with no dishes. Place a thermometer in a glass on the bottom rack to measure actual water temperature. Should reach 65°C minimum.
💡 Temperature below 55°C indicates a failed heating element.
- 6
Listen for pump noise
During the wash cycle, listen near the base of the machine for a buzzing or humming sound. If completely silent during wash, the pump has likely failed. A weak hum means reduced pressure.
💡 A healthy pump produces steady, rhythmic water noise.