The short answer
A Costway compact dishwasher heats a small volume of water with a small heater, so a cold result usually means it started with cold water rather than that the heater failed. On a tap-connected machine run the hot tap first; on a tank-fill machine fill it with hot water. That single habit fixes most of these complaints.
What you are actually seeing
- The tub and the dishes are cold at the end of the cycle — Means: on-page
- Nothing dries at all — Means: on-page
- The cycle runs much longer than it used to — Means: on-page
- Grease is left unmoved on plates — Means: on-page
- An eco or quick cycle is selected — Means: on-page
- The machine will not run a cycle at all — Means: different-fault — Go to: costway-dishwasher-wont-start
- Dishes are clean but wet with a warm tub — Means: different-fault — Go to: costway-dishwasher-cleaning-performance
- Body: Match what you see before you take anything apart. The tub and the dishes are cold at the end of the cycle. Nothing dries at all. The cycle runs much longer than it used to. Grease is left unmoved on plates. An eco or quick cycle is selected. Some near-miss symptoms belong on a different page: The machine will not run a cycle at all points at a start or supply fault, covered on costway-dishwasher-wont-start; Dishes are clean but wet with a warm tub points at a drying rather than a heating problem, covered on costway-dishwasher-cleaning-performance.
Causes, ranked for this machine
- A cold fill, because the hot tap was not run first or the tank was filled with cold water — Why this rank: First because it is free, extremely common and produces exactly this symptom on a perfectly healthy machine
- An eco or quick cycle selected that heats little or not at all — Why this rank: Compact machines offer short cycles that trade temperature for time, and owners leave them selected
- The machine connected to the cold tap on a mixer, or the tap set to cold — Why this rank: A tap-connected machine takes whatever the tap is set to at the moment of connection
- A very small heater working against a cold start in a cool room — Why this rank: Explains a machine that warms slowly rather than not at all
- A failed heater or thermostat — Why this rank: Last because it needs a part and everything above it is free
- 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: A cold fill, because the hot tap was not run first or the tank was filled with cold water. First because it is free, extremely common and produces exactly this symptom on a perfectly healthy machine. Next most likely: An eco or quick cycle selected that heats little or not at all. Compact machines offer short cycles that trade temperature for time, and owners leave them selected. Third: The machine connected to the cold tap on a mixer, or the tap set to cold. A tap-connected machine takes whatever the tap is set to at the moment of connection. Fourth: A very small heater working against a cold start in a cool room. Explains a machine that warms slowly rather than not at all. Fifth: A failed heater or thermostat. Last because it needs a part and everything above it is free.
What to check, in order
- Run the hot tap until it is genuinely hot before connecting, or fill the tank with hot water
- Select a normal or intensive cycle rather than an eco or quick one
- Confirm the tap is set to hot on a mixer
- Feel the door partway through a cycle to judge whether the machine heats at all
- Body: Each check rules out the causes above it. First, run the hot tap until it is genuinely hot before connecting, or fill the tank with hot water. Second, select a normal or intensive cycle rather than an eco or quick one. Third, confirm the tap is set to hot on a mixer. Fourth, feel the door partway through a cycle to judge whether the machine heats at all.
Checks you can safely make yourself
- Run the kitchen hot tap until the water is hot to the hand, then connect the adapter and start immediately — Tools: none — Time estimate: a few minutes
- Fill an internal tank with hot water from the tap rather than cold, up to the marked level — Tools: jug — Time estimate: a few minutes
- Select a normal or intensive cycle with no eco or quick option, and run a normal load — Tools: none — Time estimate: one cycle
- Check the mixer tap is set to hot rather than to a blended or cold position before connecting — Tools: none — Time estimate: a few minutes
- Partway through a hot cycle, feel the outside of the door: it should be noticeably warm if the machine is heating — Tools: none — Time estimate: one cycle
- Body: Checks an owner can make with the machine unplugged or by watching a short cycle. Step one: Run the kitchen hot tap until the water is hot to the hand, then connect the adapter and start immediately. Tools: none. Time: a few minutes. Step two: Fill an internal tank with hot water from the tap rather than cold, up to the marked level. Tools: jug. Time: a few minutes. Step three: Select a normal or intensive cycle with no eco or quick option, and run a normal load. Tools: none. Time: one cycle. Step four: Check the mixer tap is set to hot rather than to a blended or cold position before connecting. Tools: none. Time: a few minutes. Step five: Partway through a hot cycle, feel the outside of the door: it should be noticeably warm if the machine is heating. Tools: none. Time: one cycle.
Safety first
Safety
Unplug the machine before removing any panel. The heater sits in the base of the tub with mains terminals nearby and it stays hot after a cycle, so do not reach into the base immediately after a wash. 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 filled with genuinely hot water, a normal cycle is selected and the tub is still cold partway through. That leaves the heater, the thermostat or the control, which are 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: Does Not Clean or Dry](/blog/costway-dishwasher-cleaning-performance) - [COSTWAY Dishwasher: Controls, Display or Error Code](/blog/costway-dishwasher-control-fault)
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
