Whitegoods Help article

Faults on Pressure System

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Quick Answer

The pressure system detects water levels in the drum using a sealed tube, a pressure chamber bottle, and a pressure switch. A blocked pressure chamber bottle is the most common fault – it traps air pressure and stops the machine spinning or causes overfilling. Always clear a blockage before suspecting the switch itself.

The pressure system on a washing machine tells the machine when water has reached the correct level and when the drum is empty. When something goes wrong with it, the machine can overfill, refuse to spin, or abort its programme entirely.

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Important

All the symptoms described in this article have other possible causes. Never assume the pressure system is at fault without ruling out other causes first. A full understanding of how the system works is essential before attempting diagnosis. See: how a washing machine controls water levels.

What Is the Pressure System?

The pressure system consists of several connected components: a pressure chamber bottle at the base of the outer drum, a length of narrow tubing, and a pressure switch. Its function is straightforward – to signal to the washing machine when water inside the drum has reached the set level, and when the drum is empty after draining. Without these signals, the machine cannot control water intake or spin correctly.

The Pressure Switch

Pressure switches are normally very reliable and are usually the last component to suspect. Before considering a faulty switch, all other causes – especially a blocked pressure chamber bottle – should be ruled out first.

A switch stuck in the on position will make the machine think water is present when there is none, causing it to skip or refuse the fast spin. A switch stuck in the off position will tell the machine the drum is empty when it is not, causing it to overfill. Neither of these symptoms is exclusively caused by a faulty switch – a blockage in the pressure system is a far more likely explanation for the switch appearing to be stuck.

Modern Pressure Switches

Older pressure switches used mechanical contacts operated by air pressure and remained largely unchanged in design for over 40 years. Modern pressure switches use small coils with magnets inside, producing different resistance readings depending on the air pressure applied. These newer designs have fewer moving parts and should in theory be equally reliable, though diagnosing them is more difficult without knowing the expected resistance values for a specific model.

The Pressure Tubing

The narrow tube running between the pressure chamber bottle and the pressure switch must be completely airtight. Damage to the tube, or air leaks at either connection point, will cause a loss of air pressure. Without a sealed system, sufficient pressure cannot build up to activate or hold the pressure switch, which can result in the machine overfilling.

Inspect the full length of the tube for cracks, splits, or loose connections at both ends.

The Pressure Chamber Bottle

The pressure chamber is a small plastic bottle at the base of the outer drum where the pressure tube connects. Blockages here are the most common cause of pressure system faults.

If the chamber becomes blocked with detergent residue or debris, water inside the chamber cannot drain away when the machine empties. This traps air pressure in the tube, holding the pressure switch in the on position and making the machine think the drum is still full. The result is that the machine will not proceed to a fast spin.

A blockage can also prevent water from entering the chamber at all, which can cause the machine to take in too much water or overfill. This type of blockage needs to be more solid to produce this symptom, as the volume of water in the tub can sometimes force its way past partial blockages into the bottle – but once inside, even a small amount of water cannot escape past the blockage when draining.

Pneumatic Door Locks and the Pressure Tube

On some older washing machines (more common on 1990s models), a branch of the pressure tubing connects to a pneumatic door interlock. Air pressure from the same system is used to hold the door locked when water is present. A blockage in the pressure chamber can therefore also trap air in the branch leading to the door lock, preventing the door from opening even after the water has been pumped away. See: different types of door locks.

Fixing a Blocked Pressure System

For a step-by-step guide to diagnosing and clearing a blocked pressure system, see: how to clear a blocked pressure system.

Other Symptoms Linked to the Pressure System

The following symptoms can also be caused by pressure system faults – though as with all symptoms in this guide, other unrelated faults can produce the same results:

Pressure system faults can be difficult to diagnose and easy to misdiagnose.

Frequently Asked Questions

What does the pressure system do on a washing machine?

It detects when water inside the drum has reached the correct level and when the drum is empty after draining. It uses a sealed air tube connected to a pressure chamber bottle and a pressure switch to send these signals to the machine’s control system. Without accurate signals, the machine cannot control water intake or spin correctly.

What causes a washing machine to overfill?

A common cause is a fault in the pressure system – either a blocked pressure chamber bottle preventing the pressure switch from activating, damage to the air tube causing a loss of pressure, or in rarer cases a faulty pressure switch. However, overfilling can also be caused by a faulty water inlet valve, so pressure system faults should not be assumed without proper diagnosis. See: washing machine overfilling.

Why won’t my washing machine do a fast spin?

If the pressure system is at fault, the machine may believe the drum still contains water and refuse to spin to avoid flooding. A blocked pressure chamber bottle is the most common cause – it traps air pressure and holds the pressure switch in the on position. However, a failed drain pump, blocked filter, or other unrelated fault can produce the same symptom. See: washing machine not spinning.

Is a faulty pressure switch likely?

Pressure switches are very reliable components and are usually the last thing to suspect. If the pressure switch appears to be stuck – whether on or off – the most likely explanation is a blockage in the pressure chamber bottle holding the system in a fixed state, not a failed switch. Clear any blockage and retest before considering switch replacement.

Last reviewed: April 2025.

Discussion

47 Comments

Grouped into 26 comment threads.

JPG 3 replies Hi, I have a hoover OPH 714D washing machine, when i switch the machine on everything seems normal but when i choose a program the drain pump starts working and the door locks but no water is in the machine. I tried opening the door of the machine emptied a bucket of clean water maybe something else happenes but the water was emptied and the drain pump continued on working. I am to check the pressure switch by blowing and maybe trying to hear some clicking noises, i will then go to the pressure chamber which maybe there is any blockage. Any pointers please maybe you had a similar problem.

Hi, I have a hoover OPH 714D washing machine, when i switch the machine on everything seems normal but when i choose a program the drain pump starts working and the door locks but no water is in the machine. I tried opening the door of the machine emptied a bucket of clean water maybe something else happenes but the water was emptied and the drain pump continued on working. I am to check the pressure switch by blowing and maybe trying to hear some clicking noises, i will then go to the pressure chamber which maybe there is any blockage.
Any pointers please maybe you had a similar problem.

Andy Trigg (Whitegoodshelp)

Likely replying to JPG

Hello JPG. A fault on the pressure system could cause the machine to think it already has water in and stop it from taking in water. However, if it thinks it already has water in it should start turning the drum and “washing”. Such faults can also cause the heating element to energise which is a very bad thing with no water inside.

So if it isn’t turning the drum back and forth it’s unlikely to be a pressure system fault. I would start at this article Washing machine won’t fill with water

However, if it starts a cycle by running the pump (which is normal) but then the pump doesn’t stop running it won’t be a fault with filling. This is because the pump should stop before it tries to take in water. If the pump doesn’t stop running it is stuck. A fault on the pressure system might be a cause but if so it shouldn’t work on the spin cycle either. Does it spin OK on a spin only cycle?

Jean Paul

Hi, your article was very informative but i need specific places where i need to check due to the continuous draining. You mentioned that “Various things can go wrong causing symptoms described below but all these symptoms have other possible causes too”, from your experience where do i need to start in sorting out the problem

Patrick Lovering 3 replies This sounds like a problem I'm having with my hoover washing machine, It fills for about five seconds then stops. goes through the program with hardly any water in the drum and then stops with an E03 drain problem message. The machine drains well though. I have replaced the water valves to no avail, and there is a good rush of water going in for the 5 seconds. The pressure switch appears to be working the pipe to it is clear, and there is no improvement when the pressure tube is removed. Any ideas? Patrick I' seem to remember having this problem before now, and pressing a combination of buttons to reset the program?

This sounds like a problem I’m having with my hoover washing machine, It fills for about five seconds then stops. goes through the program with hardly any water in the drum and then stops with an E03 drain problem message. The machine drains well though. I have replaced the water valves to no avail, and there is a good rush of water going in for the 5 seconds. The pressure switch appears to be working the pipe to it is clear, and there is no improvement when the pressure tube is removed. Any ideas?
Patrick

I’ seem to remember having this problem before now, and pressing a combination of buttons to reset the program?

Andy Trigg (Whitegoodshelp)

Likely replying to Patrick Lovering

Hello Patrick. If you remove the pressure tube the washer should overfill. If it isn’t then I’d suspect the pressure switch though I can’t guarantee it.

patrick

Ok thanks Andy, yes have removed tube and blown it clear, left it removed but still wouldn’t fill, disconnected the switch and no joy, does it fail open or closed do you know?

Andy Trigg (Whitegoodshelp)

Likely replying to Patrick Lovering

Thanks Patrick. Which problem did you have that turned out to be the element?

Keith Grine 3 replies When I start a cycle, my washer automatically starts in the drain mode and does not start filling with water. Would a problem with the pressure switch cause this issue? Thanks

When I start a cycle, my washer automatically starts in the drain mode and does not start filling with water. Would a problem with the pressure switch cause this issue?
Thanks

Andy Trigg (Whitegoodshelp)

Likely replying to Keith Grine

Hello Keith, all modern washing machines tend to energise the pump for a short while before starting a wash cycle. It’s just to make sure the machine is empty. If it fails to fill with water after 20 or 30 seconds there could be a fault with the water supply to the machine or the water valve in the machine (check this article – Washer won’t fill with water

In relation to the pressure system, a fault on the pressure system (as described in this article above) could convince the washing machine it already has water inside and that would stop it taking any more water in. However, I would also expect that if this is the case the drum would start turning as if washing the laundry and it would also refuse to spin.

A final possibility is if by any chance there was a fault or partial blockage in the pump or plumbing resulting in the washer not being able to empty the water out properly although I would expect it to be fairly obvious that there is still some water inside the machine.

Peter Boucher

Likely replying to Andy Trigg (Whitegoodshelp)

Hi Andy, I have a Samsung Top loader (FUZZY LOGIC). As soon as I press the power on button, The cold water solenoid energizes and water is let in. The water continues to run in until the power switch is switched off. I have replaced the solenoid with a new one but still does the same thing. Any Ideas?? I i disconnect the cold water, select a cycle and select only the hot water. the machine works fine?? Your assistance will be greatly appreciated.

Andy Trigg (Whitegoodshelp)

Likely replying to Peter Boucher

Hello Peter, it doesn’t sound related to the pressure system. The valve must be getting a live supply and a neutral return from somewhere. Insulation faults can cause weird things to happen. You would need an engineer with an insulation test meter to check it out.

Tom 1 reply Thank you very much for this detailed information. My LG washing machine developed a fault code which suggested a fault on the drain cycle. I changed the pump but still had the same problem a few days later. I wish that I’d seen your site earlier as clearing the pressure chamber resolved the problem completely. It was surprising how much gunk had built up over the past 2 years. Thank you for finding the time to offer such great support. Regards Tom

Thank you very much for this detailed information.
My LG washing machine developed a fault code which suggested a fault on the drain cycle. I changed the pump but still had the same problem a few days later.
I wish that I’d seen your site earlier as clearing the pressure chamber resolved the problem completely. It was surprising how much gunk had built up over the past 2 years.
Thank you for finding the time to offer such great support.
Regards
Tom

Wayne 1 reply Hi, I have a Bosch front loader with a tricky problem and hope you may be able to offer a solution. I have been an appliance repairman for some 15 years and have never seen this before. The machine overfills on every cycle and when pressure switch closes on its first notch, it begins the wash cycle. However it will continue to fill until the drain pump activates on the second notch, and when it reaches its normal water level the inlet valves close. This happens on every fill stage. On occasion and intermittently, the water valves will re-activate on the wash cycle, sometimes getting a few pulses of power to the inlet valves. I suspected a fault in the control PCB, so I switched it out for another from another working machine and got the same problem. The pressure switch and inlet valves are working normally and I have checked for any other pressure systems abnormalities-none found. The machine is not syphoning and has no leaks. The bizarre thing is, that when it activates pressure switch on 1st. notch; if I turn the tap off and immediately turn back on again, the water stops. Can you shed any light on this?

Hi, I have a Bosch front loader with a tricky problem and hope you may be able to offer a solution. I have been an appliance repairman for some 15 years and have never seen this before.
The machine overfills on every cycle and when pressure switch closes on its first notch, it begins the wash cycle. However it will continue to fill until the drain pump activates on the second notch, and when it reaches its normal water level the inlet valves close. This happens on every fill stage.
On occasion and intermittently, the water valves will re-activate on the wash cycle, sometimes getting a few pulses of power to the inlet valves.
I suspected a fault in the control PCB, so I switched it out for another from another working machine and got the same problem.
The pressure switch and inlet valves are working normally and I have checked for any other pressure systems abnormalities-none found.
The machine is not syphoning and has no leaks.
The bizarre thing is, that when it activates pressure switch on 1st. notch; if I turn the tap off and immediately turn back on again, the water stops.
Can you shed any light on this?

Andy Trigg (Whitegoodshelp)

Likely replying to Wayne

Hello Wayne. On first reading it sounds like the water valve is possibly sticking if it stops filling once you have turned off the water supply and back on? It is indeed a very strange one. Have you tried replacing the water valve?

The only other rare fault I’ve had with pressure systems is if there is a small air leak where the pressure chamber hose fits onto the pressure chamber or actually somewhere on the hose itself or of course where the hose fits onto the pressure switch. In such a case the air pressure that holds the pressure switch position is constantly escaping so the washing machine overfills. Please let us know if you manage to fix this.

Fred 1 reply Hello! I’d just like to thank you for this article and will leave my experience here to help any others with this issue. I have a samsung washing machine that started to give a 5e error. I checked all the obvious stuff, like the filter and blockages in the drainage plumbing. However when initiating a cycle the machine would simply run the drain pump until it timed out and gave 5e again. I removed the detergent drawer and stuck the garden hose in there to manually fill the machine and check if the drainage system was working, like and behold it was pumping out all the water I put in perfectly. After reading your article I thought I’d try the presssure switch, I simply removed the tube from the pressure switch and tried again, boom, working fine. Clearly there was a blockage at the other end of the tube. I blew down it as hard as I could and felt something give, probably a nice mix of soap scum, scale and other debris that had formed a a bung in the tube. Also (very carefully) forced a couple of gob fulls of water down it to make sure it was clear. I blew down again regularly over the next hour to dry it out. Put the lot back together and all is working as it should. So the Samsung 5e error can indeed be caused by the pressure switch system. Certainly worth checking before a call out. Thanks again!

Hello!

I’d just like to thank you for this article and will leave my experience here to help any others with this issue. I have a samsung washing machine that started to give a 5e error. I checked all the obvious stuff, like the filter and blockages in the drainage plumbing. However when initiating a cycle the machine would simply run the drain pump until it timed out and gave 5e again. I removed the detergent drawer and stuck the garden hose in there to manually fill the machine and check if the drainage system was working, like and behold it was pumping out all the water I put in perfectly. After reading your article I thought I’d try the presssure switch, I simply removed the tube from the pressure switch and tried again, boom, working fine. Clearly there was a blockage at the other end of the tube. I blew down it as hard as I could and felt something give, probably a nice mix of soap scum, scale and other debris that had formed a a bung in the tube. Also (very carefully) forced a couple of gob fulls of water down it to make sure it was clear. I blew down again regularly over the next hour to dry it out. Put the lot back together and all is working as it should. So the Samsung 5e error can indeed be caused by the pressure switch system. Certainly worth checking before a call out.

Thanks again!

Andy Trigg (Whitegoodshelp)

Likely replying to Fred

Thanks Fred. Just bear in mind that clearing a blockage in this way is more often than not only temporary. Just keep an eye on it in case the fault comes back. Blockages in the pressure system can also cause an appliance to overfill.

Victoria Savill 1 reply Our washing machine shows an error code mid cycle which prevents it draining. Through trial and error we've found that it will work if the pipe isn't connected and it drains into the sink instead. Do you think this is a problem with the pressure system or something else. We've just moved into a new house and this is only the second time we've used the machine which was in the propert already.

Our washing machine shows an error code mid cycle which prevents it draining. Through trial and error we’ve found that it will work if the pipe isn’t connected and it drains into the sink instead. Do you think this is a problem with the pressure system or something else. We’ve just moved into a new house and this is only the second time we’ve used the machine which was in the propert already.

Richard 1 reply Hi I have moved house and transported the washing machine which is an LG direct drive 8K, the washer has been very reliable, however after installing at my new home and switching it on for its first wash, it started overfilling, the washer normaly uses very little water so to see the drum filling up and not switching off was very strange, it also seems to have stopped detecting load size. Any ideas? Thany you

Hi
I have moved house and transported the washing machine which is an LG direct drive 8K, the washer has been very reliable, however after installing at my new home and switching it on for its first wash, it started overfilling, the washer normaly uses very little water so to see the drum filling up and not switching off was very strange, it also seems to have stopped detecting load size. Any ideas?

Thany you

Andy Trigg (Whitegoodshelp)

Likely replying to Richard

Hello Richard. As this fault appears to have been introduced by moving it (which is unusual) you’d have to check that the thin pressure tubing hose is connected OK to the pressure switch and the pressure chamber although I can’t imagine how they could have come off even if you’d thrown it down the stairs. Alternatively maybe there’s a blockage in the pressure chamber bottle and not using it for some days has allowed it to solidify. If you can’t see anything call an engineer.

steve foster 1 reply Hi, Thanks for your articles they are very informative, I have a beko washing machine which doesn't drain fully on a normal programme, it only drains fully when I do an additional spin and drain, would this be a pressure switch problem?

Hi, Thanks for your articles they are very informative, I have a beko washing machine which doesn’t drain fully on a normal programme, it only drains fully when I do an additional spin and drain, would this be a pressure switch problem?

Andy Trigg (Whitegoodshelp)

Likely replying to steve foster

Thanks Steve. It’s unlikely because the pressure switch just waits for a signal as to whether the water is at the correct level when filling and when the water has pumped away during spin. If anything the pressure system faults (commonly a blockage) happen when the water does pump out but the signal doesn’t get through.

If the water doesn’t drain out fully and needs an additional spin and drain it’s most likely to be caused by a partial blockage in the pump, the pump filter or possibly at the u-bend under the sink (if plumbed into the sink.) Try troubleshooting here –

How do I clean my pump filter (where is the pump filter?)
Washing Machine Won’t Drain Water

Michael Hulsey 1 reply I stumbled onto your site while searching for information on how the modern washing machine knows how much water to put in the tub. After reading your article I think I understand how the washing machine turns on and off the water going into the tub. I also understand a pressure switch is used to determine how much water is in the tub, but not how much should be in the tub. How does the washing machine know when there is a small load of laundry and it only needs a small amount of water. Or that there is a large load in the washer requiring more water. I hope I made my question clear. Michael-

I stumbled onto your site while searching for information on how the modern washing machine knows how much water to put in the tub.

After reading your article I think I understand how the washing machine turns on and off the water going into the tub. I also understand a pressure switch is used to determine how much water is in the tub, but not how much should be in the tub. How does the washing machine know when there is a small load of laundry and it only needs a small amount of water. Or that there is a large load in the washer requiring more water.

I hope I made my question clear.

Michael-

Andy Trigg (Whitegoodshelp)

Likely replying to Michael Hulsey

Hello Michael. They should be able to tell the weight of the load of laundry inside the drum by the resistance needed to turn the drum. They can monitor the strain load on the motor, how much power it needs, how smoothly it is running etc. Also some loads will naturally take more water if they are absorbent. Loads that don’t contain absorbent laundry will fill up quicker.

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