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Why Has my Pressure Washer Lost Pressure? | Pressure Washer Repair Guide

You’re mid-way through cleaning your car, and out of nowhere, your pressure washer suddenly loses pressure. A sudden loss of pressure can force you to abandon a job well before it’s finished - leaving you, or potentially your customers feeling less than impressed. Whether it’s a slight drop in pressure or a complete loss of it, try not to panic as nine times out of ten, the fix is quick and easy.

To help you troubleshoot your pressure washer, here are some of the most common reasons it is losing pressure when in use and how to fix them.

Pressure washer repair - Common low pressure causes

Some of the most common causes of low or no pressure when using a pressure washer are really easy to fix. If you’re experiencing issues with your machine, be sure to check these causes as part of your pressure washer repair troubleshooting.

  • Blockages
  • Holes and leaks
  • Low-pressure water supply
  • Wrong size hose
  • Unloader valve
  • Pressure regulator issues
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What happens to a pressure washer without enough water?

All pressure washers have a minimum water pressure level that’s needed to work. When running a pressure washer below this level, or without any water at all, the machine will likely burn out.

The reason for this is that the inbound water acts as a coolant, preventing the water compressor, o-rings and other internal parts from becoming heat-damaged. To provide sufficient cooling, water needs to be able to flow through the machine at a set pace, drawing heat away from it as it leaves the nozzle. If the pressure is too low, the water heats up like a pan on the stove, and the machine will burn out.

Burnout damage can be hard to fix, so as soon as you notice your water pressure is too low, stop using your machine and begin troubleshooting the cause.

Common pressure washer troubleshooting

Before you start to take a closer look at your pressure washer, be sure to disconnect it from the mains power and turn off the inbound water supply.


The number one cause of low or no pressure when using a pressure washer is a blocked or worn nozzle. Blocked nozzles will prevent water from escaping, while a worn nozzle will allow too much water to pass through, causing the pressure to drop. Friction between the water and the nozzle, along with chemicals and minerals, will cause the nozzle to widen with regular use, meaning it’s important to replace your nozzles regularly.

An easy way to tell if your nozzles need to be replaced is to look at the spray pattern when in use. If it is irregular or lacking definition, it’s time to put a new nozzle on the wand. If you have already checked and replaced the nozzle on your washer and the water pressure is still too low, the problem may be with your water supply.

PW 360 Nozzle

Water Supply

The water supply you use will play a huge part in how much pressure you receive from your washer. If you are trying to connect to an extremely low-pressure tap without a pump, then your machine will struggle to work. If you have access to another tap with higher pressure, connect your inlet hose to it and fire it up. If it works as it should, then your water supply is the problem.

Another potential issue is air in the system. To clear any air out, simply switch your washer to the off position, remove the nozzle from the wand, and then pull the trigger.


Next up is the inlet hose. On average, most machines require a flow of at least 4L per minute to work properly, so if your inlet hose has kinks, leaks or has a narrow diameter, achieving this is going to be challenging. The average size of a garden hose is ⅝” in diameter, which is what many people will use with their pressure washer. However, a ¾” diameter hose will usually provide better water supply and pressure.

If your hose appears to have no issues, you will want to look at the inlet filter screen. Algae, debris and organic matter can block the filter, preventing water flow. If you have recently changed your high-pressure outlet hose, you may have one that is slightly too large for your washer. An increase of just ¼” in diameter can significantly impact pressure. Switch back to the original high-pressure hose, and if it fixes the issue, you know where the fault is.

Steel armed extension hose

Connections & O-Rings

Worn o-rings and loose connections can allow water and pressure to escape before reaching the nozzle. With the machine turned off, run water through it and look for any leaks or damage at the connections, wand and nozzle. You should also try to listen for any hissing sounds. If you notice water leaking from anywhere but the nozzle, check o-rings one by one, replacing them as needed. If water is leaking from any of the connections, take some PTFE thread tape and create a better seal.

Unloader Valve

The unloader valve works by diverting water from the pump to the bypass when the pressure washer is not spraying and adjusting the rate of pressure as and when needed. If you notice a drop in water pressure, first check your nozzles for any wear or tear. If the nozzles are OK, then you will need to adjust the unloader valve to increase pressure.

When adjusting the unloader valve, it is recommended to do so in tiny increments, testing the pressure between each adjustment. It is important to have the washer running and the spray activated whilst making the adjustments. Try to avoid making the water pressure too high as this could damage the unloader valve and other internal components.

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What if I can’t find a cause?

Most of the time, pressure washer repair problems can be performed at home in a few simple steps, meaning you can get back to work in no time at all.

However, if after running through all of the above troubleshooting tips, you still can’t pinpoint the cause of your low-pressure issue, the best thing to do is to take your pressure washer to your local Husqvarna dealer for repair.

Husqvarna Pressure Washers are manufactured using high-quality materials and parts and come backed with a generous warranty. Find your perfect pressure washer online, or visit your local Husqvarna dealer for more.