Cheapest and most likely first.
Power, properly
Socket, RCD, plug fuse, extension lead. Long thin extension leads also drop enough voltage on start-up to stop a motor that is otherwise fine.
Thermal cut-out
Pressure washers and vacuums both have one. It resets after cooling. If a machine stops when it is hot and works again the next morning, this is the answer and it is not a fault.
Interlocks
Steam machines refuse to heat with the cap loose or the tank empty. Wet and dry vacuums cut suction when the float is up. Floor washers refuse to run with the dirty tank unseated. Reseat everything and listen for the click.
Batteries
A pack stored flat over winter may need a long slow charge before it shows any sign of life, and a pack that was charged below freezing may not recover at all.
Robots
A robot that will not start is usually a dirty charging contact, a wheel drop sensor with hair around it, or a full dust bag with the sensor triggered. All three are two-minute fixes.
Then call it
If it has power and no protection device is engaged, stop. Opening a pressure washer or a steam boiler at home is not a home repair.
The questions we hear
My pressure washer stopped mid-job and now does nothing.
Most likely a thermal cut-out. Domestic washers are built for intermittent use, and holding the trigger shut for long periods heats the pump because the water has nowhere to go. Unplug it, leave it for thirty minutes and try again — and let go of the trigger between passes in future.
Is it worth checking the RCD before anything else?
Yes, along with the plug fuse and the socket. Outdoor sockets trip and the trip is not always obvious. It costs nothing to check and it is the most common cause of a machine that is completely dead rather than partly working.
Last reviewed 2026-08-16
