5 Common Pressure Washer Faults and When to Call for a Repair

When a pressure washer stops performing, it usually does not fail all at once — it gives you warning signs first. Spot them early and you can often fix the problem cheaply or avoid it altogether. Ignore them and a small issue can turn into an expensive pump failure at the worst possible moment.

Here are the five faults we see most often in our workshop, what causes them, and when it is time to call in a professional.

1. Loss of pressure

The most common complaint by far: the machine runs, but the cleaning power has dropped off.

Likely causes:

• A blocked or worn nozzle — the single most frequent culprit.
• A clogged inlet filter starving the pump of water.
• An inadequate water supply or a kinked inlet hose.
• Worn pump seals or valves on higher-hour machines.

What to try first: Check and clean the nozzle and inlet filter, and make sure your water supply is strong and unrestricted. If the pressure is still low after that, the issue is likely inside the pump — and that is a job for a professional.

2. Pulsing or surging pressure

If the pressure rhythmically surges and drops while you hold the trigger, the machine is telling you something is wrong inside.

Likely causes:

• Worn or dirty pump valves.
• A failing unloader valve.
• Air trapped in the system or a restricted water supply.

What to try first: Bleed the system by running water through with the trigger open before starting, and confirm the supply is adequate. Persistent pulsing usually points to worn valves, which should be inspected and replaced before they damage the pump further.

3. Water leaks

A few drops are not always a crisis, but leaks should never be ignored for long.

Likely causes:

• Worn O-rings or seals at hose and lance connections — usually cheap and simple to fix.
• A cracked hose or fitting.
• Leaks from the pump head itself, which indicate worn pump seals.

What to try first: Tighten connections and replace worn O-rings on hoses and lances. If water is coming from the pump head, stop using the machine and have it serviced — running a pump with failing seals will accelerate the damage.

4. The machine won't start

Frustrating, but often straightforward.

On electric machines:

• Check the power supply, plug, fuse and any reset (TSS) switch.
• Look for a tripped thermal cut-out — let the motor cool and try again.
• Inspect the cable for damage.

On petrol machines:

• Check the fuel and oil levels.
• Inspect the spark plug and air filter.
• Make sure the engine controls are set correctly for starting.

What to try first: Work through the basics above. If an electric motor is dead with good power, or a petrol engine will not fire despite fuel, spark and air, it needs professional attention.

5. Overheating or cutting out

If the machine gets hot and shuts down, it is protecting itself — and warning you.

Likely causes:

• Running the machine in bypass (trigger off) for too long, which heats the recirculating water.
• Restricted water supply.
• A motor or pump under strain from another underlying fault.

What to try first: Avoid leaving the machine running with the trigger off for extended periods, and make sure it has a full, unrestricted water supply. Repeated overheating despite good practice suggests a deeper fault that should be checked.

When should you call for a repair?

As a rule of thumb, the simple checks above are fair game for any user. Call a professional when you see:

• Pressure problems that survive a nozzle and filter clean — the pump likely needs attention.
• Persistent pulsing or surging — worn valves that will worsen.
• Leaks from the pump head — a clear sign of internal wear.
• Electrical faults — never attempt internal electrical repairs yourself.
• Any unusual grinding or knocking noise — stop and get it checked.

The honest answer is that catching a fault early almost always costs less than waiting for a full breakdown. A worn seal is a minor repair; the seized pump it causes is not.

Fast, expert repairs across the UK

Real Kleen offers both workshop servicing and mobile callouts, with the aim of getting you back up and running quickly — often within 24 hours. Whatever the brand, our 40 years of experience means we can diagnose and fix the fault fast.

Got a pressure washer playing up? Contact Real Kleen and let's get it sorted.