The short answer
Poor cleaning in a Costway compact dishwasher is nearly always about load size, water temperature and the single small spray arm rather than a failed part. These machines have far less spray capacity than a built-in, so overloading is the dominant cause. Reload, start with hot water and clean the arm, and most complaints resolve.
What you are actually seeing
- Items in the middle or the back of the rack stay dirty — Means: on-page
- A white film on glasses and on the inside of the tub — Means: on-page
- Dishes are clean but soaking wet at the end — Means: on-page
- Cleaning got worse after the machine was loaded more heavily — Means: on-page
- Detergent is left undissolved in the dispenser — Means: on-page
- Water remains in the base at the end of the cycle — Means: different-fault — Go to: costway-dishwasher-drainage-failure
- The tub is cold at the end of the cycle — Means: different-fault — Go to: costway-dishwasher-heating-failure
- Body: Match what you see before you take anything apart. Items in the middle or the back of the rack stay dirty. A white film on glasses and on the inside of the tub. Dishes are clean but soaking wet at the end. Cleaning got worse after the machine was loaded more heavily. Detergent is left undissolved in the dispenser. Some near-miss symptoms belong on a different page: Water remains in the base at the end of the cycle points at a drain fault, covered on costway-dishwasher-drainage-failure; The tub is cold at the end of the cycle points at a heating or supply fault, covered on costway-dishwasher-heating-failure.
Causes, ranked for this machine
- Overloading, so the single spray arm cannot reach the load — Why this rank: First because a compact machine has far less spray capacity than owners expect and the temptation to fill it is strong
- Blocked jets on the spray arm, or an arm stopped by a tall item — Why this rank: The pattern of what stays dirty maps directly onto which jets are blocked
- Cold or cool fill water, on a tap-connected or tank-fill machine — Why this rank: Compact machines rely on the water you give them, so a cold fill weakens both washing and drying
- A fouled filter recirculating dirty water — Why this rank: Small filters fill quickly on a machine with no disposer of its own
- No rinse aid, or the wrong detergent for a compact machine — Why this rank: Ranked here because it drives the drying result and the film on glassware
- Body: Ranked for a countertop or portable dishwasher that connects to the kitchen tap with a quick-connect adapter or fills from an internal tank, and drains through a hose into the sink. Most likely: Overloading, so the single spray arm cannot reach the load. First because a compact machine has far less spray capacity than owners expect and the temptation to fill it is strong. Next most likely: Blocked jets on the spray arm, or an arm stopped by a tall item. The pattern of what stays dirty maps directly onto which jets are blocked. Third: Cold or cool fill water, on a tap-connected or tank-fill machine. Compact machines rely on the water you give them, so a cold fill weakens both washing and drying. Fourth: A fouled filter recirculating dirty water. Small filters fill quickly on a machine with no disposer of its own. Fifth: No rinse aid, or the wrong detergent for a compact machine. Ranked here because it drives the drying result and the film on glassware.
What to check, in order
- Run one cycle with half the usual load and compare the result
- Spin the spray arm by hand and clear every blocked jet
- Run the hot tap before connecting, or fill the tank with hot water
- Clean the filter and fill the rinse aid
- Body: Each check rules out the causes above it. First, run one cycle with half the usual load and compare the result. Second, spin the spray arm by hand and clear every blocked jet. Third, run the hot tap before connecting, or fill the tank with hot water. Fourth, clean the filter and fill the rinse aid.
Checks you can safely make yourself
- Load the machine to half its usual level, run a normal cycle and compare the result against a full load — Tools: none — Time estimate: one cycle
- Spin the spray arm by hand to check it turns freely, then hold it to the light and clear blocked jets with a cocktail stick — Tools: cocktail stick, torch — Time estimate: a quarter of an hour
- Run the kitchen hot tap until hot before connecting the adapter, or fill the internal tank with hot water — Tools: jug — Time estimate: a few minutes
- Unplug the machine, lift out the filter, rinse it under a hot tap and scrub the mesh with a soft brush — Tools: brush, gloves — Time estimate: a quarter of an hour
- Fill the rinse aid reservoir and use a detergent suitable for a compact machine, then judge over several cycles — Tools: rinse aid, detergent — Time estimate: several cycles
- Body: Checks an owner can make with the machine unplugged or by watching a short cycle. Step one: Load the machine to half its usual level, run a normal cycle and compare the result against a full load. Tools: none. Time: one cycle. Step two: Spin the spray arm by hand to check it turns freely, then hold it to the light and clear blocked jets with a cocktail stick. Tools: cocktail stick, torch. Time: a quarter of an hour. Step three: Run the kitchen hot tap until hot before connecting the adapter, or fill the internal tank with hot water. Tools: jug. Time: a few minutes. Step four: Unplug the machine, lift out the filter, rinse it under a hot tap and scrub the mesh with a soft brush. Tools: brush, gloves. Time: a quarter of an hour. Step five: Fill the rinse aid reservoir and use a detergent suitable for a compact machine, then judge over several cycles. Tools: rinse aid, detergent. Time: several cycles.
Safety first
Safety
Unplug the machine before removing the filter or the spray arm, and wear gloves against broken glass. Do not open the door mid-cycle on a hot wash: the steam released is hot enough to scald. Unplug the appliance or switch off its breaker before removing any panel. A capacitor can hold a charge after the power is off. unplug-before-service
Where the owner fix ends
Call a technician, or claim under warranty, when the machine is lightly loaded, the arm turns freely with clear jets, hot water is used, the filter is clean and rinse aid is in use, and items still come out soiled. That points at the wash pump, which is inside the machine.
Nearest pages of the same kind
Generalized information
This page is generalized across the Costway dishwasher line. Countertop machines with an internal tank, countertop machines on a tap adapter and rolling portable machines share the ranking above but not every part, and this page does not cover a specific model or control revision. Family- and model-specific pages, where they exist, are linked below.
Links: - [Common COSTWAY Dishwasher Problems](/blog/costway-dishwasher-problems) - [COSTWAY Dishwasher: Abnormal Noise or Vibration](/blog/costway-dishwasher-abnormal-noise) - [COSTWAY Dishwasher: Controls, Display or Error Code](/blog/costway-dishwasher-control-fault) - [COSTWAY Dishwasher: Cycle Will Not Run or Complete](/blog/costway-dishwasher-cycle-fault)
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
