Read the reviews on any pressure washer accessory and you will find one-star entries saying “does not fit my machine”. In almost every case it fitted fine and needed a two-dollar adapter. Here is the whole fitting question, once.
The two standards
M22 threaded. A screw fitting with a 22mm thread. This is what most homeowner machine outlets and most high-pressure hose ends use. Tighten by hand and it seals on an O-ring.
1/4-inch quick connect. A push-and-click coupler with a sliding collar. This is what almost every accessory uses — nozzle tips, surface cleaners, foam cannons, turbo nozzles.
A typical machine therefore has M22 at the outlet and the hose, and quick connect at the wand end. Which is why accessories usually fit the wand but not the machine directly.
The real trap: M22-14 versus M22-15
M22 comes in two internal sizes, measured across the center pin or seat: 14mm and 15mm. The external thread is identical. They will screw together and they will not seal, so you get a spray from the joint and conclude the part is faulty.
14mm is the common homeowner size — Sun Joe, Greenworks, Ryobi, Westinghouse electrics and most hoses. 15mm turns up more on some gas machines and European-made units.
To tell which you have: look into the male fitting on your machine outlet. The raised center section is either about 14mm or about 15mm across. A cheap caliper or a steel rule answers it in a few seconds. Your manual will usually state it too.
The fix: convert everything to quick connect, once
Buy a small adapter set and fit it permanently. You end up with quick connect at the machine outlet, the hose ends and the gun, and from then on every accessory pushes on in a second with no thinking.
The pieces worth owning: M22 to 1/4-inch quick connect for the gun and wand ends, and 3/8-inch male to 1/4-inch female for accessories built around the larger coupler. Between them they cover every combination a homeowner meets.
Use PTFE tape on threaded joints, hand-tight plus a nudge, and keep spare O-rings — a weeping joint is far more often a perished O-ring than a wrong size.
While you are at it: the swivel
A 360-degree swivel fitted between the hose and the gun stops the hose twisting into loops behind you. It is a fitting rather than an accessory, it costs a few dollars, and it is the upgrade people most often wish they had made sooner.
Three habits that prevent fitting problems
Release pressure before disconnecting anything. Squeeze the trigger with the machine off until flow stops. Disconnecting under pressure is how O-rings get damaged and how fittings get fired across a yard.
Push the collar fully home on a quick connect, and give the accessory a tug. A half-seated tip exits under pressure.
Keep grit out. A quick connect dropped in dirt and reconnected is how nozzles block. An inlet water filter handles the supply side.
With fittings settled, the accessory decisions are in the accessories kit page, and if a surface cleaner is on the list, check the flow as well as the fitting.
