Display shows E01 and brewing will not start or stops immediately after pressing the brew button.

Safety first: Unplug the coffee maker before handling the reservoir or tipping the unit. Allow any hot surfaces to cool.

• Check reservoir seating: Remove the water reservoir completely, then firmly reseat it. Make sure it is pushed all the way down and back until it is fully aligned with the base.
• Inspect reservoir magnet/float: Look inside the reservoir for the small float or magnet assembly that moves up and down with the water level. Ensure it moves freely and is not stuck with scale or debris. Rinse and gently clean with warm water and a soft brush.
• Clean sensor area: On the base of the coffee maker where the reservoir sits, wipe the sensor window or recess with a soft, slightly damp cloth to remove coffee residue or mineral buildup. Dry thoroughly.
• Test with fresh fill: Fill the reservoir to at least the minimum line, reseat it, plug the unit back in, and try a brew cycle again.
• If E01 persists: The internal reservoir level sensor or control board may be faulty. Discontinue use and contact a qualified appliance technician or Calphalon support.