What does it mean when a dishwasher is not washing clean?
A dishwasher that is not washing clean is short of spray pressure, heat, detergent or water. The residue shows which.
- Food left on one rack: a spray arm is blocked or cannot turn.
- Grit in glasses and cups: the filters are clogged.
- White film or spots: the salt or rinse aid is empty.
- Greasy dishes and a part-dissolved tablet: the water is not heating.
Common causes of a dishwasher not cleaning dishes properly
The common causes run from poor loading to a weak circulation pump, simplest first.
At a glance
| Cause | Typical sign | Who fixes it |
|---|---|---|
| Poor loading | One area stays dirty | You can check this |
| Clogged filters | Grit in glasses and cups | You can check this |
| Blocked spray arm jets | Food left on one rack | You can check this |
| Detergent | Grease, tablet residue | You can check this |
| Salt or rinse aid empty | White film, cloudy glasses | You can check this |
| Heater or temperature sensor | Greasy dishes, cool tub | Technician |
| Circulation pump | Weak spray, arms barely turn | Technician |
| Inlet valve | Dry wash, tablet whole | Technician |
- 1
The load blocks the spray arms
You can check thisSpray arms must turn freely and water must reach every item. A tall pot or pan handle stops an arm or blocks the detergent door. Spin each arm by hand before you start.
- 2
The filters are clogged
You can check thisThe filters in the tub floor strain food from the wash water. Clogged filters send grit back through the spray arms. Wash them under a tap with a soft brush. Clogged filters also cause a dishwasher not draining.
- 3
The spray arm jets are blocked
You can check thisSmall jets in each spray arm drive the arm round and spray the dishes. Seeds, pips and limescale block them. Remove the arms, clear each jet with a toothpick and rinse.
- 4
The detergent is old, damp or underdosed
You can check thisTablets and powder lose strength when stored damp. Too little detergent leaves grease, and a quick programme may not dissolve a tablet fully. Use fresh detergent on a normal programme.
- 5
The salt or rinse aid is empty
You can check thisDishwasher salt regenerates the built-in water softener, and rinse aid helps water run off. In hard-water areas and on borehole water, empty reservoirs leave white film and cloudy glasses. Refill both.
- 6
The water is not heating
TechnicianThe heater element heats the wash water and a temperature sensor reports it to the control. With a failed heater or sensor, dishes stay greasy and the tub is cool at the end. A technician tests both.
- 7
The circulation pump is weak
TechnicianThe circulation pump forces water through the spray arms. A worn or partly blocked pump gives a weak spray, and the arms barely turn. A technician repairs or replaces it.
- 8
The inlet valve is not letting enough water in
TechnicianThe inlet valve fills the sump at the start of each stage. With a blocked or failed valve, the wash sounds dry and the tablet stays whole. Check the tap and hose. A technician replaces the valve.
What you can safely check yourself
- Switch off and unplugSwitch off at the plug point and unplug before you remove any parts.
- Clean the filtersTwist out the filters, wash them and remove debris from the sump.
- Clean the spray armsUnclip or unscrew each arm, clear the jets and rinse it through.
- Refill salt and rinse aidUse dishwasher salt only, and top up the rinse aid.
- Reload and testLoad so both arms turn freely. Run a hot programme with fresh detergent.
When to stop and call a technician
Stop and unplug the dishwasher if you smell burning, the machine trips the earth leakage or water appears on the floor. Stop if the water stays cold, the pump hums without spraying or the fault returns after cleaning. Do not remove panels or touch the heater terminals, wiring or control board.
Still having trouble with your dishwasher?
Our technician comes to your home, usually the same day. The R450 call-out falls away if you go ahead, and you get a fixed price in writing before any work starts.
How a technician diagnoses a dishwasher not washing properly
- Reads the fault codesThe technician runs the service test programme and reads stored codes.
- Checks the fillThe water level and inlet valve are checked.
- Tests the heating circuitThe heater element, temperature sensor and heater relay are measured.
- Tests the circulation pumpThe pump motor and impeller are checked, and the spray system is flushed.
Why is my dishwasher not heating water or drying dishes?
A dishwasher that is not heating water has a failed heater element, temperature sensor or heater relay. Most dishwashers fill with cold water and heat it themselves. Drying relies on a hot final rinse and rinse aid, so a dishwasher not drying dishes often has the same heating fault or no rinse aid. Plastic items always dry poorly. Heating faults need a dishwasher repair technician.
Is a dishwasher that is not cleaning properly worth repairing?
Repair usually makes sense when
- The fault is blocked filters, spray arms or a dosing problem
- The heater, sensor or inlet valve has failed
- The tub, racks and door seal are in good condition
Replacement is worth considering when
- The circulation pump and control board have both failed
- The tub or base is rusted or leaking
- Parts for the model are no longer available