Display shows “ADD WATER” even though the water reservoir is full; brewing will not start.

Safety first: Unplug the coffee maker and let it cool completely before working on it.

Step-by-step:

• Check reservoir seating: Remove the water reservoir, empty it, rinse, and firmly reseat it. Many Cuisinart models use a magnet/float or molded tab that must align with a sensor in the base.
• Clean the sensor area: If your model has a clear window or float, inspect for mineral scale. Soak the reservoir in a 1:1 white vinegar and water solution for 20–30 minutes, then scrub gently around the float or indicator with a soft brush.
• Free a stuck float: Gently tap or shake the reservoir to free a stuck float. Verify that the float moves freely up and down when the reservoir is filled and emptied.
• Inspect base contacts: On removable-reservoir models, inspect the bottom of the reservoir and the mating contacts or optical window on the base. Wipe dry and clean with a damp cloth; do not flood the base with liquid.
• Reset and test: Reassemble, fill with fresh water, plug in, and try a brew cycle. If the message persists, the internal water level switch or sensor wiring may be faulty.
• When to stop: If you suspect a failed sensor or control board, do not open the sealed base unless you are qualified. Contact Cuisinart support or a professional technician.