I can no longer adjust the pressure onmy karcher hds601c eco pressure washer, the knob turns the same as it always has but no difference in pressure? any advice appreciated

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If nozzle is partially clogged, it can cause unloader valve to shift back and forth from high pressure to bypass. Air in the feed line can also cause this symptom. Some Karcher models have auto start/stop system which can behave this way if worn out, or out of adjustment.

you can find the parts for the kacher hot pressure washer on this site
http://septimus-spares.co.uk/hot-pressure-washer/karcher/hds-745m-eco/

ok im a technician... cheak d power swtich. i think most of karcher power knob switch they got a error problem.

To get the soad to come out you will need to adjust your machine to low pressure. You can do this by turning the knob at the end of the lance and then your machine will **** chemical.

The Knob is broken off of the Plastic Shaft..to the switch assembly.
A new switch assembly is available direct from Karcher.

You should check with the manufacturer for a pump kit for this washer.

If it's a good unit they should have the stuff to freshen up the pump so it runs like new.

Have you checked the oil level in the pump itself? Make sure its to level and the oil is clean and free of water contamination. It will look like milk if its got water in it.

If you live in a very cold climate always remember to winterize the pump or it could freeze and be damaged beyond repair.

Look for +/- on knob and turn + direction for max pressure.

Dear Pajodi,
I just came across your problem. I have just joined FIXYA, and solved various Karcher problems. First of all with all respect, the shop from where you bought the machine, must have told you all necessary instructions to operate your machine.
Now the soap always works on low pressure. So if you have a variable lance, turn it to low pressure. You can also remove the lance, and the soap will surely starts to work. With turbo lances, the soap system does not work. This concludes that the soap does not work when high pressure is used. Bigger machines do spray soap at high and low pressures. But these have regulating knobs, to swith off and on, the soap supply.
Regards,
MG.