Have you been having issues with your dishwasher not cleaning your dishes as well as normal?

While there may be many reasons for this, one of the main reasons could be that your dishwasher is failing to heat up the water properly. After all, cold water simply cannot wash dishes as effectively as hot water.

If your dishwasher isn’t getting the water hot enough, make sure to check the drain filter isn’t clogged and the hot water supply works elsewhere. If it does, the hot water might be due to a faulty thermostat, heating element, or circuit board.

If your dishwasher’s temperature is trying to be too cool, then read on and let’s go through each of the possible causes and solutions.

6 Reasons Why Your Dishwasher Isn’t Heating Water

The Drain Filter Is Clogged

The drain filter in your dishwasher is designed to capture and trap scrap particles of food, dirt, and debris that come off of your dishes as they are being washed. When the filter gets too dirty or becomes blocked, the suction power of the dishwasher’s motor will be significantly reduced. As a result, the unit’s ability to heat up may be impacted.

Therefore, take a look at the drain filter to see if it is severely dirty and/or clogged. If it is, remove it from the dishwasher. Fill the sink with warm, soapy water and allow the filter to soak for about 30 minutes to an hour. For a more heavy-duty cleaning, use white vinegar.

Before replacing the filter, use a damp cloth to clean the area around where the filter goes in the dishwasher to remove any left behind food particles. Rinse the filter thoroughly and replace it in the dishwasher. Hopefully, this will solve the problem and the water in your dishwasher will heat up now.

Clean Dishwasher Filter
It’s important to frequently clean the filter to avoid losing suction power from the dishwasher’s motor.

The Dishwasher Is Hooked Up to the Hot Water Supply

Dishwashers are sort of fancy in the way that they can be hooked up to the hot or cold water supply and still work effectively. This is because dishwashers are manufactured with heating elements and thermostats that work to control the temperature of the water.

However, some homeowners prefer to still connect their dishwashers to the hot water supply in an effort to be more energy efficient and save on their utility bill. Of course, some dishwasher models don’t allow this.

If your dishwasher is hooked up to the cold water supply and is failing to heat the water, then the problem likely lies within the thermostat or heating element, so see below.

Now, if your dishwasher is hooked up to the hot water supply and is having trouble heating up the water, then you should take a look at the supply line as opposed to the dishwasher itself. The supply line may be kinked or damaged, requiring repair or replacement.

In addition, there is something else to take into consideration when you have your dishwasher connected directly to the hot water supply. Modern dishwashers tend to have a maximum water temperature outlined in the manual, and when that temperature is exceeded, the dishwasher may shut off or reduce the wash cycle, leaving your dishes half cleaned.

The Thermostat Is Defective

The thermostat is an indirect component involved in heating the water in your dishwater, as it is responsible for informing other dishwasher components like the heating element about what temperature the water should be. Therefore, if the thermostat is defective and unable to “speak” to these other components, then the water temperature will not be accurate throughout the wash cycle.

The dishwasher essentially won’t know when to turn the heating element on or off in order to keep the water at the necessary temperature to wash the dishes properly. There will be no regulation of temperature whatsoever.

The good news is that it is relatively easy to test the condition of the thermostat. A multimeter is needed to do this. You’ll touch one probe to a terminal. You’ll want to measure for voltage. If the reading is 0, then this means the thermostat isn’t getting any power and is indeed defective.

Even better news, if the problem is the thermostat, it is a relatively inexpensive part to replace it. Unfortunately, the location of the thermostat is a bit difficult to get to, as it is underneath the appliance.

The Heating Element Is Faulty

If you determine that the thermostat is not the problem, then your issue may be the heating element, which means the heating process inside of the dishwasher itself. This is an issue that can occur regardless of whether your dishwasher is hooked up to the cold or hot water supply.

The heating element is responsible for more than controlling the temperature of the water, as it also aids in the drying of the dishes. This component is generally built to last for some time, but it is possible for it to burn out or become damaged as a result of an electrical fault.

The resistance levels of the heating element can be tested with a multimeter. The readings that you see on the multimeter should be somewhere between 15 and 30 ohms. If the multimeter is reading anything higher, the heating element has suffered some kind of damage and needs to be replaced.

Of course, the issue could also be within the wiring or the control board. Similar to the thermostat, the heating element is a cheap part to purchase. In addition, if you are good with your hands, it won’t be a difficult component to replace. Otherwise, you should leave the repair to a professional service repairperson.

Heating element in optimal conditions
While your dishwasher may be hooked up to the hot water line, every dishwasher uses a heating element to heat the wash water up to the appropriate temperature.

The Electrical Wiring Is Damaged

All of the components of your dishwasher are connected by electrical wiring. Without those electric wires, your dishwasher would not work—at least not properly. Over time, these wires can deteriorate, especially as a result of mechanical issues and excessive heat from the electrical current.

Due to this deterioration, your dishwasher may stop heating. If this ends up happening and the electrical wires are the cause, they will need to be replaced. This is something that you can do on your own, but you should only do it if you feel comfortable doing so. Otherwise, it is recommended to have a professional perform the repair.

The Circuit Board Is Malfunctioning

The circuit board plays a very important role in the overall functioning of your appliance, as it is essentially the brain of the dishwasher. The circuit board is responsible for the management of all of the unit’s functions, such as the motor, water, heating, etc.

Therefore, when something is wrong with the circuit board, something is amiss with the entire dishwasher. If you have checked all of the other components listed above and it all appears fine, then the problem with your dishwasher not heating up water properly could very well lie within the circuit board.

Because you are essentially dealing with the brains of the entire unit, it is recommended to have a repair technician assess and diagnose a circuit board issue with your dishwasher.


Thank you for reading this article, and hopefully, you have now concluded what is wrong with your dishwasher and why it wasn’t heating up the water. When you run into any other issues with your dishwasher or other home appliances, please check out our other articles.