Safety first: Unplug the coffee maker. Do not attempt to run it again until it has fully cooled and been inspected.

Check power outlet: Plug another appliance into the same outlet to confirm proper voltage. Avoid using power strips or extension cords.
Reset attempt: With the unit unplugged, wait 10 minutes, then plug back in and try a brew cycle. If E04 appears immediately and no heating occurs, internal heater protection has likely opened.
Feel for warmth: Carefully touch the warming plate and sides after a failed brew attempt (with power disconnected). If they remain completely cold, the heating circuit is not energizing.
Do not bypass safety devices: The thermal fuse and thermostats are critical safety components. Never attempt to bypass them.
Professional repair: Replacing the thermal block, thermal fuse, or heater relay requires opening the chassis and working with mains wiring. Contact a qualified technician or Calphalon service for heater circuit diagnosis and replacement.

Display shows E04 and the coffee maker shuts down or never heats the water.

Possible Causes