Machine will not start a coffee cycle, display shows E01 shortly after power-on.

Safety first: Unplug the coffee maker before removing any covers. Do not work on a hot boiler or brew unit.

• Check water tank and seating: Remove the water tank, rinse it, and ensure the outlet valve at the bottom moves freely. Reinstall firmly so the tank valve is fully opened.
• Bleed air from the system: Fill the tank completely with fresh water. Power the unit on and run a hot water cycle (if available) 2–3 times to purge air from the lines.
• Inspect inlet filter and hose (plumbed-in models like CTL/CTL636 series): Close the water shutoff valve. Disconnect the inlet hose and clean the small mesh filter at the hose connection. Check for kinks or crushing along the hose and correct them.
• Descale the hydraulic circuit: If the machine has not been descaled recently, run a full descaling program using Bosch-approved descaler. Limescale can restrict flow and cause E01.
• If E01 persists: The flowmeter or inlet valve may be defective. Replacement typically requires removing the top and side panels and disconnecting water lines; if you are not experienced with appliance repair, contact a Bosch service technician.