Cordless vacuum shows E12 and shuts off when the brush is activated on certain floor types

Safety first: Remove the battery and disconnect the floor nozzle.

• Check brush height adjustment: If your Kärcher nozzle has a height or carpet/hard floor selector, move it through all positions several times to free any stiffness. Ensure it clicks into place.
• Clean sensor area: Some nozzles have optical or mechanical sensors near the front or underside. Use a soft brush to remove dust and fibers from any small windows or levers.
• Test on different surfaces: After reassembly, test on hard floor and low‑pile carpet. If E12 appears only on one surface, the sensor or mechanism for that mode may be faulty.
• Inspect cable and connector: Check the nozzle-to-wand connector for bent pins or damaged contacts. Replace the wand or nozzle if the connector is damaged.
• Persistent E12: The floor type sensor PCB inside the nozzle likely needs replacement. On many models this means replacing the entire powered nozzle.