Display shows E04 and the coffee maker shuts down; sometimes accompanied by a beeping alarm. Unit may feel very hot.

Safety first: Immediately unplug the coffee maker. Allow it to cool completely (at least 45–60 minutes) before touching the base or heater area.

• Inspect for blockage: Remove the filter basket and carafe. Check the drip outlet and shower head holes for coffee grounds or scale buildup. Clean with warm water and a soft brush or toothpick (do not enlarge the holes).
• Descale thoroughly: Fill the reservoir with a T-fal-approved descaling solution or a 1:1 mix of white vinegar and water. Run a full brew or cleaning cycle, then let the solution sit in the system for 15–20 minutes before finishing the cycle. Rinse with 2–3 full tanks of clean water.
• Check ventilation: Ensure the coffee maker is not pushed against a wall or under a low cabinet that traps heat. Provide at least several centimeters of clearance around the unit.
• Reset attempt: After cooling and descaling, plug the unit back in and run a water-only cycle. If E04 returns quickly, stop using the machine.

Persistent E04 indicates a failing thermostat or thermal fuse. These are safety-critical components and should only be replaced by a qualified technician.