The answer, before the detail
On a l2 dishwasher, poor cleaning is usually overfilled racks and nested items rather than a worn-out machine. Water has to reach every surface at temperature; anything that interrupts that — a blocked arm, a packed rack, a dirty filter — shows up as grit or film on the load.
The symptoms, and the ones that mean something else
- Results got worse gradually over months — Gradual change is build-up — limescale, grease, a slowly blocking arm — rather than a component that has failed.
- Dishes on the top rack clean, bottom rack poor, or the other way round — One arm is not doing its job. Which rack fails tells you which arm to look at.
- Only heavily soiled items come out dirty — That is often a cycle choice: a short eco cycle is not intended for baked-on food.
- NEAR MISS — the machine will not complete a cycle — If it stops partway rather than washing badly, the cycle fault is the page to read, not this one.
What actually causes this, ranked
- Overfilled racks and nested items — The commonest single version of this is a tall item in the lower rack that stops the upper arm turning. The machine runs its full cycle, uses its detergent and heat, and cleans half the load. First, because nothing else on the list explains as many of these calls, and ruling it out costs nothing but a few minutes. The platform behind a smaller badge is usually a common contract build, so the causes that lead here are the generic ones that class is known for.
- Blocked spray arm jets — The arms spray through a row of small holes, and those holes block with limescale, seeds and label fragments. As they close, the arm spins more slowly and the pattern collapses, so coverage falls away long before anything stops completely. Second on the list — a real suspect, and the next one that can be settled by looking rather than measuring.
- Dirty water being recirculated over the load — A blocked filter also restricts flow to the pump, so pressure at the arms falls and coverage drops at the same time. One neglected part therefore produces two different complaints. This far down the list because it needs the two above ruled out before the evidence for it means anything.
- Incoming water not hot enough, or a short cycle chosen — A long run of pipe between the water heater and the machine means the first fill is whatever was standing in that pipe. Running the kitchen hot tap until it is hot before starting a cycle is a real, measurable change. Last, and the reason the order matters: it is the least likely of the four, and the three above are quicker to settle.
Check in this order, and why
- Look for items laid flat over the lower arm or bowls nested together — Water cannot reach an inside surface that another dish is covering. First, and it costs nothing but a minute of attention.
- Take each arm off and hold it up to the light — Blocked jets are visible immediately, and a rinse under a hot tap clears most of them. Next, because it takes the same few minutes and covers the other likely half.
- Smell the tub after a cycle — A dishwasher that smells is a dishwasher whose filter is overdue, and the two complaints usually arrive together. Third, and the last thing worth doing before the phone comes out.
What to do, step by step
- Reload with space between items and nothing blocking either arm — Face soiled surfaces towards the centre, and keep tall items to the sides.
About 15 min
- Clean the arm bearing and the feed port before refitting — Grease on the spindle is what stops an arm turning at speed.
Tools: clothAbout 15 min
- Rinse the filter stack under a hot tap with a brush and refit it locked home — Check the coarse and fine parts separately; debris hides between them.
Tools: brushAbout 20 min
- STOP HERE if the next step needs a meter on live terminals — That is the line between an owner check and a service call, and it is not a line worth crossing for a fault that is already narrowed to two causes.
Before you open anything
Safety
Turn the power off at the wall before any panel comes off or a hand goes into the sump. Never tape or defeat the door latch to make the machine run with the door open: that interlock is the only thing that stops a tub of near-boiling water being sprayed into the kitchen.
When this becomes a service call
Stop and call at the point where the next step would be testing a heater or a pump. Everything before that is loading, cleaning and consumables, and it fixes the large majority of poor-wash complaints.
Nearest pages of this class
What this page does not cover
This page is deliberately generalized across the l2 dishwashers it covers. It does not carry model-specific wiring, torque values or component resistance figures — those belong on the page for your family, and that page takes precedence where it exists.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
