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How to Diagnose Dishwasher Leaking and Heating Problems

Leaking or heating problems with your dishwasher can have a number of causes. In this article, we're going to run you through identifying the potential reasons, as well as guiding you on the steps to take to fix them.

Safety first!

Make sure that your appliance is switched off and fully disconnected from the mains before you attempt to diagnose or repair any faults it may be experiencing.

Due to sharp edges on certain areas of a dishwasher, we also highly recommend that you wear protective gloves before proceeding with any repairs or maintenance.

How to diagnose dishwasher leaking and heating problems

Let's get stuck in. To diagnose and repair any potential leaking or heating problems with your dishwasher, simply follow the how-to video or the guide below.

Dishwasher Leaking - External Leaks

A dishwasher can leak in two ways; externally and internally. First of all, let's take a look at the causes of external leaks and how to fix or prevent them.

Leaking Door Seal

A dishwasher door seal isn't actually a complete seal, but rather a splash seal to deflect water inside the appliance. This means that, if water is rising any higher than the bottom seal, it will leak externally. This is usually due to a dishwasher that is leaning too far forwards. To fix this, you simply need to readjust your dishwasher and make sure that it is level again.

Incorrect Detergent Usage

If your dishwasher is level and you are still dealing with external leaking, the issue could be due to the detergent you are using. If you use the wrong detergent - or too much - it can cause a lot of foam which leads to leaking. In this case, you should simply use less detergent to avoid this happening again, as well as making sure you're using the correct one too.

You can also use a dishwasher cleaner and descaler during a cycle, which will help to flush out any blockages and keep the appliance running and draining properly. We would recommend using a product like this on a regular basis anyway, as your dishwasher will function much more smoothly if it is consistently kept clean and cared for.

Condensation Leaks

Leaks can also happen due to condensation rising from the top of the dishwasher door at the end of a cycle. If your dishwasher is kept beneath a worktop or surface, the steam can condense on the underside of the surface and drip down. If this is the issue, simply make sure you give the top of the dishwasher and the underside of the work surface a wipe down with a cloth to prevent any excess leaking.

If there is a large amount of condensation, however, it might be that the door seal is letting too much out. If this is the case, you may need to replace the door seal. You can learn how to do this by watching this video on our YouTube channel.

Leaking Hoses

Another potential cause of external leaks is damage to the drain hose and the inlet hose such as rips and tears that will let water out. You should also make sure to check the washers that can be found at the ends of the inlet hose, pictured above. If the rubber has perished in any way, the washers won't form a proper seal, which can cause leaking. If you are having these issues with any of these parts, replace them.

Dishwasher Leaking - Internal Leaks

Now let's look at internal leaks.

What to do if you get a dishwasher leaking error code

The base of the dishwasher is actually a very shallow tray with an anti-flood switch connected to it. It is designed so that, if there is any internal leakage, the water has room to build up to a low level in the tray.

If there is a build-up of water in the tray, it will gradually raise the polystyrene float, which in turn will activate the anti-flood switch once it gets to a certain level. You will know if there is a flood in the tray if your dishwasher emits a combination of lights and beeps or displays an error code relating to this fault when you turn it on. You may also hear the pump running continuously as it tries to drain all of the excess water away.

You can also check if there is any water in the base by tipping the dishwasher slightly to one side and seeing if any water runs out. Make sure the appliance is switched off and unplugged from the mains before doing so.

To reset the error, simply remove any water from the tray and you will notice that the polystyrene float will come back down again. This will deactivate the anti-flood switch, allowing you to use your dishwasher once again.

Causes of Internal Dishwasher Leaks

If the fault reoccurs after you've drained the water from the base you will need to investigate further to determine the cause of the internal leak inside your dishwasher. To do this, place your dishwasher on its side and remove the base. You will need to disconnect the anti-flood switch with a screwdriver so you can fully remove the base.

Now that you can see inside your dishwasher, the source of interior leakages will come from anywhere that comes into contact with water. The most likely places to leak are the sump, pump and hoses. You will want to check these for any holes or damage and replace the damaged part if you do find anything.

If there is no damage but you can see rust or discolouration around the area beside the sump, the issue may be that the seals in the sump are damaged. To look for this, you will need to remove the sump and check the seals for dirt or damage. If they are dirty, you can simply clean them, but they will need replacing if they are damaged before refitting the sump.

If you still can't find any problems with the seals in the sump, the flooding may have been caused by too much foaming. If this is the case, you can reassemble the dishwasher, pop the anti-flood switch and base back on and try the dishwasher again.

Dishwasher Heating Issues

You will usually know if your dishwasher has heating problems if it won't finish a wash cycle. Instead, it will keep washing while it waits for the water to get up to temperature - but, if there is a heating problem, it will never reach the temperature it's supposed to.

Before we go any further, let's take a look at the two different types of dishwasher heaters.

Standard element type

The first is a standard element type. This is usually located beneath the tub.

Flow-through heater

The second is a flow-through heater type, located in the dishwasher base as pictured above.

Testing a Heater With a Multimeter

You can test both types of heater and check whether they're working or not using a multimeter on a low resistance setting. To do this, disconnect the heater and place the probes into the terminals of the heater. For a working heater, you will want a reading of around 30 ohms, though it could vary about 5 ohms either way.

Using A Multimeter To Test a Thermostat and Thermal Cut-Out

If your dishwasher uses a standard element type of heater, it may also have a thermostat or thermal cut-out fitted somewhere close to it - usually on the underside of the tub. You can use your multimeter to test to see if the thermostat is faulty too. You will know if the thermostat is faulty if the multimeter reads as an infinite circuit and gives no reading on the meter. If this is the case, you may need to replace the thermostat. If the thermostat is working, however, the issue may be a short circuit. You will be able to see if this is the case if the multimeter reads less than a couple of ohms.

If your dishwasher uses the flow-through heater, it will likely be fitted with a thermal sensor somewhere in the door. The thermal sensors do not tend to fail, and they are usually only available as part of the control board. So, if you've carried out all of the other checks and you still can't find a fault, the chances are you just need to replace the control board to resolve the issue.

Caring for your dishwasher

As mentioned earlier in this article, it's important to make sure you regularly clean your dishwasher in order to keep it running and doing its job properly. Regularly using dishwasher cleaner and descaler for a cycle will help to keep your dishwasher in great shape and functioning effectively. For more dishwasher repairs and advice, don’t forget to check out our other advice articles.

We hope this article has been useful in helping you to diagnose any leaking or heating problems your dishwasher might be having. Don't forget to join our mailing list below to receive exclusive offers and discounts on household appliance spare parts and accessories, as well as tips and advice on fixing and maintaining.

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