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Kärcher Faults
5 documented Kärcher faults, covering K3, K7, K2, K5 and K4. Each entry sets out the symptom as owners report it, the most likely cause, the checks that confirm or rule it out, and whether the repair is worth doing. Everything here is compiled and cross-checked from manufacturer documentation and owner reports — the sources are listed on every page.
Documented faults
- Kärcher K3
Pressure washer runs and sprays water normally, but no detergent comes through even with a full bottle fitted
Detergent only draws in low-pressure mode, and the tiny suction filter and hose feeding it from the bottle clog or kink easily — the machine is often not faulty, just set wrong or blocked at the pickup
Pumps & Pressure 2026-09-29 - Kärcher K7
Pressure washer won't switch on at all, or starts and runs for a while before stopping and refusing to restart
Usually not a fault: the motor's built-in overload breaker has tripped from a long hard run and needs an hour to cool, or the supply reaching the machine (extension lead, weak socket, wrong voltage) is too weak to start it. A damaged mains cable is the one version of this that needs attention rather than a wait
Pumps & Pressure 2026-09-28 - Kärcher K2
Water drips or leaks from the underside of the housing, including when the machine is switched off, sometimes alongside the motor not stopping when the trigger is released
A failed internal seal inside the pressure-switch/cylinder-head unit at the top of the pump — a sealed, solvent-welded assembly rather than a serviceable part
Pumps & Pressure 2026-08-29 - Kärcher K5
Pressure washer runs and passes water but never reaches full pressure, or surges and fluctuates badly, even though the motor sounds normal
Restricted or aerated flow through the pump — a blocked high-pressure nozzle, a silted-up inlet sieve, or trapped air — rather than a worn pump; a sticking bypass valve in the pump head is the less common and more expensive cause
Pumps & Pressure 2026-08-23 - Kärcher K4
Pressure washer switches itself on and off repeatedly (pulsing) with the trigger released
A small pressure leak downstream of the pump — the auto-stop system sees pressure decay and restarts the motor to top it back up
Pumps & Pressure 2026-06-08
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Pumps & Pressure
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