Kärcher HD 1090 Service Handbook page 27

Troubleshooting and basic settings
Unit switches on and off continuously
Unscrew control pressure injector
Control pressure injector defective
– Control pressure injector of overflow valve is
washed out or the O-rings are defective.
– Unscrew the injector; the inside diameter must
be 2.4 + 0.05 mm. Replace if necessary.
– Grease the O-rings with silicone grease and
remount.
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