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Dishwasher isn't cleaning the dishes properly

The cycle runs to completion but plates come out gritty, filmed or still greasy. Usually blocked spray arms, a clogged filter, or salt and rinse aid that ran out months ago — rarely an actual component failure.

Verdict

You can fix this yourself

No special tools or qualifications needed

Urgency
Not urgent

About 3 hr to work through

Typical cost

Free to £260

DIY: Up to £40 in parts

What causes it, most likely first

  1. Blocked spray arm jets

    Most likely

    Debris lodges in the jets and the arms stop reaching the top rack. Classic sign is the upper basket cleaning noticeably worse than the lower one.

    How to check: Unclip the arms and check every jet is clear by flushing them under a tap.

    Spray arm£12–£40 for the partDIY

  2. Clogged filter

    Most likely

    A grease-varnished filter recirculates dirty water back over the dishes for the whole cycle.

  3. Salt or rinse aid empty

    Common

    Without salt the softener stops working and limescale films everything, especially glassware. Without rinse aid, water sheets and dries as spots. Both reservoirs need topping up on a schedule.

    How to check: Check the salt and rinse-aid indicator lights on the fascia.

  4. Overloading or blocked spray path

    Common

    A large tray or a tall pan blocks the spray arm from rotating. Spin each arm by hand after loading to check it clears everything.

  5. Water not heating

    Occasional

    A failed heater leaves you washing in cold water, so grease never lifts. Dishes come out cold and wet at the end of the cycle rather than warm and steaming.

    Heating element / flow heater£25–£90 for the partEngineer

  6. Failed circulation pump

    Occasional

    Water is never driven up the spray arms with enough force. The cycle completes normally but nothing gets cleaned.

    Circulation / wash pump£45–£130 for the partEngineer

What to check, in order

  1. Clean the filter properly

    Twist out the filter stack and wash it in hot soapy water with a brush until light passes evenly through the mesh. Wipe out the sump underneath.

    15 minWashing-up brush, Gloves

  2. Clear the spray arms

    Unclip both arms — usually a quarter turn or a single nut — and flush them under a tap. Clear blocked jets with a cocktail stick rather than a needle, which can enlarge them.

    10 minCocktail stick

  3. Top up salt and rinse aid

    Fill the salt reservoir and set the water hardness for your area in the machine settings. Fill the rinse aid dispenser. In a hard-water area this alone fixes most film and spotting complaints.

    10 min

  4. Check your loading

    After loading, spin each spray arm by hand through a full turn. If anything catches, rearrange. Do not let large flat items shield the rest of the load.

    5 min

  5. Run a hot maintenance cycle

    Run the hottest programme empty with a dishwasher cleaner or a cup of white vinegar in the base to strip accumulated grease from the pump and hoses.

    120 min

  6. If dishes come out cold, get it looked at

    Cold dishes at the end of a hot programme mean the heater is not working. On many machines the heater is integral to the pump, so get the full quote before committing — it can approach the price of a replacement.

    10 min

Need an engineer for this?

We list 75 dishwasher repair businesses across the UK. Diagnostic callouts typically start around £55, and many will put that towards the repair if you go ahead.

Find dishwasher engineers near you

Parts you might need

Typical UK prices for the part alone, before fitting. Worth knowing before you accept a quote — the part is often a small share of what a repair is priced at.

  • Spray arm

    The rotating arms that fling water at the dishes. Usually just needs the jets clearing rather than replacing.

    £12–£40

  • Heating element / flow heater

    Heats the wash water. On modern machines it is integrated into the pump housing, which raises the part cost considerably.

    £25–£90

  • Circulation / wash pump

    Drives water up the spray arms. A failed one gives you a cycle that runs to completion with dirty dishes at the end.

    £45–£130

Worth repairing, or replace it?

At the top of this range the repair costs a significant share of a graded replacement, which typically starts around £190. Worth getting the quote first, then deciding — on a machine under about five years old a repair usually still wins.

Work out if it's worth fixingCompare graded dishwashers

Is there an error code on the display?

If your dishwasher is showing a code, that will narrow the diagnosis a lot further than symptoms alone.

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