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How to Diagnose Dishwasher Leaking and Heating Problems

A leaking dishwasher can be caused by a number of reasons, in this eSpares video Josh looks at how to diagnose the cause of a leak, as well as heater problems. We will look at what parts of the appliance could be causing the issue you are experiencing, and hopefully help you to find the specific fault that is at blame.


This video shows an example on how to remove or replace the part on a typical machine, some models may be different but the procedure should be similar.

What You Will Need:

Step 1 - Switch Off Your Appliance

Safety First! Please ensure that you have disconnected the appliance from the mains before starting any repair.

Caution: Due to the sharp edges exposed we suggest suitable Safety Gloves are worn to help prevent injury when carrying out this repair.

Dishwasher Leaking - External Leaks

There are two possible ways in which your dishwasher could possibly leak - the first is by the water leaking out side of the machine, and the second way is by leaking water internally.

The Door Seal

The door seal isn't actually a complete seal - it's just a splash seal designed to deflect any water of the door back into the cavity. Something to look out for is to check that the dishwasher is on a level or flat surface, and that it's not leaning forward (as if it is then it will cause the water level to raise in the tray)

If this raised water gets any higher than the seal, it can actually leak out the front of the machine. So make sure the dishwasher is completely level to help avoid any leakage.

The Detergent

If your dishwasher is level but you’re getting leakage from the front, it could be due to a problem with the detergent - possibly by you either using too much detergent or maybe the wrong type of detergent. If either of these is the case, it could cause a lot of foam to leak out of the front.

We would recommend that you use less detergent, but you can also run a cleaner through the system ( such as the eSpares limescale and detergent remover ) and that'll help to flush any blockages through and keep the system running properly.

eSpares Top Tip:

It's a good idea to run the clean through anyway just to make sure that the system is completely clear and you should also be cleaning a dishwasher with a proper cleaner on a regular basis anyway - just to keep the system working at its most effective.

Check For Condensation

You can also get leaks as a result of condensation forming after the dishwasher has finished a cycle. You can get steam coming out at the gap in the top of the door, and if the dishwasher is underneath a work surface this steam can condense on the underside of the work surface and then drip down onto the floor.

It is important to vent the steam after a cycle to reduce condensation forming, If you are finding that this is a problem, just grab a cloth and give the underside of the work surface a wipe. If you are finding that there's a large amount of condensation on the other hand, it might actually be that you need to replace the door seal inside (because it's letting too much steam out, and you can see how to do that in another eSpares video.

The Hoses

Leaks can also form as a result of damage to both the drain hose and the inlet hose, as if there are any tears or damage in the material of the hose then that's going to then let water out. Another thing to look out for regarding hoses is the washers that are located on the ends of the fill hose.

If the rubber has perished in any way then they're not going to be able to form a proper seal - and that's going to lead to water leaking out. If the washers have seen better days, you will need to replace them.

Dishwasher Leaking - Internal Leaks

Place the dishwasher down onto its back and we'll take a look at internal leaks. If you take off the base of the dishwasher in this video, the first thing we can see is the anti-flood switch, the base is actually a very shallow tray - and is designed so that if there is any internal leakage the water can build-up to a low-level in the tray.

The Tray

Now If there is a build-up of water in the tray it will gradually raise the polystyrene float, and once it gets to a certain level it'll activate the anti-flood switch.

You will know if there is a float in the tray, because when you first turn your dishwasher on you may get a combination all lights and beeps, and you may have the pump running continuously as it tries to drain the water away.

To check if there's any water in the base, you just need to tip the dishwasher slightly to one side and observe to see if any water runs out. If there is signs of water then that would indicate that there's a build up in the base

Proceed to remove any water, and you will notice that that'll bring the float back down and deactivate the switch, you should be able to use your dishwasher again.

A More Detailed Look Inside The Dishwasher

To get a better look inside the dishwasher, you need to remove the anti-flood switch so that you are then able to remove the base.

Once you have the base away from the dishwasher you can have a look inside - but remember that the source of the leakage will come from anywhere that obviously comes into contact with water. With this in mind the most likely places to check are the sump, the hoses and the pump.

Just have a look for any holes or damage to the material anywhere on these parts, and obviously if you do find anything you’ll just need to replace the part as necessary.

However, if you can’t find any holes in any of those parts and you can see any rust or discoloration and in this sort of area, it may be that the seals in the sump are damaged. In which case remove the sump and have a look at the seals - if they are dirty then just give them a good clean, or replace them altogether and then refit the sump.

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

Dishwasher Heating Issues

You usually know if a dishwasher has a heating problem because it won't finish a wash cycle, as it's going to keep washing while it waits for the water to get up to temperature. But obviously if there's a heating problem it's never going to do that.

Dishwashers have two different types of heaters. One is this standard element type (and this is located usually at the bottom of the tub), the other type of heater is a flow-through heater (located in the base) - and it is the flow through heater that is featured in this particular model. Now you can test both types for whether they're working just using a multimeter on a low resistance setting.

Using A Multimeter To Test The Heater

Disconnect the heater and place the probes onto the terminals of the heater, and for a working heater you're looking for reading of round about 30 ohms - although it could be about 5 ohms, either way, now that's what I'm getting about 34 or 35 ohms so that shows that this one should be okay.

Using A Multimeter To Test The Thermostat/Thermal Cut-out

If your dishwasher uses this type of flow through heater, it may also have a thermostat or thermal cut-out fitted somewhere near to it (usually on the underside of the tub).

Now if that’s faulty it's obviously going to cause a problem. You can use your multimeter to test to see if the thermostat is faulty. You will know if it is faulty if it reads as an infinite circuit and gives no reading on the meter.

On the other hand if it's working it will be a short circuit (so less than a couple of ohms). Obviously if you're not getting a short circuit reading, you may need to replace that thermostat. If your dishwasher uses this flow through heater it'll probably also be fitted with a thermal sensor somewhere in the door. The thermal sensors don't tend to fail and they’re usually only available as part of the control board. So if you've checked all these other a reasons and you can't find a fault, the chances are you just need to replace the control board to resolve the issue.

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