The short answer
A Cove dishwasher that finishes cool usually started with cold water rather than having lost its heat. The machine takes the house hot supply and manages temperature from there, and a long run from the water heater produces a cool wash, a long cycle and a poor dry all at once. Run the hot tap first before suspecting anything inside the machine.
What you are actually seeing
- The tub and the dishes are cool at the end of the cycle — Means: on-page
- The cycle runs much longer than it used to — Means: on-page
- Nothing dries at all even with rinse aid — Means: on-page
- Greasy items come out with the grease unmoved — Means: on-page
- Results changed after work was done on the kitchen plumbing — Means: on-page
- The machine will not run a cycle at all — Means: different-fault — Go to: cove-dishwasher-wont-start
- Dishes clean but wet with a warm tub — Means: different-fault — Go to: cove-dishwasher-cleaning-performance
- Body: Match what you see before you take anything apart. The tub and the dishes are cool at the end of the cycle. The cycle runs much longer than it used to. Nothing dries at all even with rinse aid. Greasy items come out with the grease unmoved. Results changed after work was done on the kitchen plumbing. 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 cove-dishwasher-wont-start; Dishes clean but wet with a warm tub points at a drying rather than a heating problem, covered on cove-dishwasher-cleaning-performance.
Causes, ranked for this machine
- A cold first fill, because the hot line was not run before the cycle — Why this rank: First because it is free, extremely common in a large kitchen with a long run from the water heater, and it produces exactly this symptom
- A supply valve throttled, or the machine plumbed to cold after kitchen work — Why this rank: A machine on the cold supply washes cool every time, and the fault dates from the plumbing work
- A house hot supply that is set low or takes a long time to reach the kitchen — Why this rank: This is a house problem rather than an appliance one, and it is worth establishing before a part is ordered
- An eco or low-temperature cycle selected on a hidden control — Why this rank: Easy to leave selected on a control you operate without seeing it
- A failed heating circuit or thermostat — Why this rank: Last because it needs a part and everything above it is free to rule out
- Body: Ranked for a premium built-in dishwasher: hard-plumbed, on a dedicated supply, installed under a worktop by a fitter, quiet by design, with hand-cleaned filtration and a condensation dry that depends on rinse aid. Most likely: A cold first fill, because the hot line was not run before the cycle. First because it is free, extremely common in a large kitchen with a long run from the water heater, and it produces exactly this symptom. Next most likely: A supply valve throttled, or the machine plumbed to cold after kitchen work. A machine on the cold supply washes cool every time, and the fault dates from the plumbing work. Third: A house hot supply that is set low or takes a long time to reach the kitchen. This is a house problem rather than an appliance one, and it is worth establishing before a part is ordered. Fourth: An eco or low-temperature cycle selected on a hidden control. Easy to leave selected on a control you operate without seeing it. Fifth: A failed heating circuit or thermostat. Last because it needs a part and everything above it is free to rule out.
What to check, in order
- Run the kitchen hot tap until it is genuinely hot, then start the cycle immediately
- Check the supply valve is fully open and on the hot line
- Select a normal or heavy cycle with any eco option switched off
- 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 kitchen hot tap until it is genuinely hot, then start the cycle immediately. Second, check the supply valve is fully open and on the hot line. Third, select a normal or heavy cycle with any eco option switched off. 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 start the dishwasher straight away — Tools: none — Time estimate: a few minutes
- Open the adjacent cabinet, find the supply valve, confirm it is fully open and trace which line it comes from — Tools: torch — Time estimate: a quarter of an hour
- Check the household water heater setting and time how long the kitchen tap takes to run hot — Tools: watch — Time estimate: a quarter of an hour
- Select a normal or heavy cycle on the top-edge control with any eco option switched off — Tools: torch — 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 switched off at the breaker, or by watching a cycle. Step one: Run the kitchen hot tap until the water is hot to the hand, then start the dishwasher straight away. Tools: none. Time: a few minutes. Step two: Open the adjacent cabinet, find the supply valve, confirm it is fully open and trace which line it comes from. Tools: torch. Time: a quarter of an hour. Step three: Check the household water heater setting and time how long the kitchen tap takes to run hot. Tools: watch. Time: a quarter of an hour. Step four: Select a normal or heavy cycle on the top-edge control with any eco option switched off. Tools: torch. 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
Switch off at the breaker before removing any panel. The heating circuit is in the base of the tub with mains terminals beside it and it stays hot after a cycle, so do not reach into the sump 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 when the hot tap runs hot, the supply valve is open on the hot line, a normal cycle is selected and the tub is still cool partway through. On an integrated machine that means removing the custom panel and drawing the machine out, which is service work.
Nearest pages of the same kind
Generalized information
This page is generalized across the Cove dishwasher line. Fully integrated machines carrying a custom cabinet panel and machines with a finished front share the ranking above but not every part, and this page does not cover a specific model, control revision or installation. Family- and model-specific pages, where they exist, are linked below.
Links: - [Common COVE Dishwasher Problems](/blog/cove-dishwasher-problems) - [COVE Dishwasher: Abnormal Noise or Vibration](/blog/cove-dishwasher-abnormal-noise) - [COVE Dishwasher: Does Not Clean or Dry](/blog/cove-dishwasher-cleaning-performance) - [COVE Dishwasher: Controls, Display or Error Code](/blog/cove-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.
