Display shows ERR4 and the coffee maker will not brew; sometimes accompanied by beeping.

Immediate action: Turn the coffee maker off and unplug it. Allow it to cool for at least 30–45 minutes.

Basic checks:

• Verify water level: Make sure the water reservoir is filled above the minimum line before starting a brew cycle.
• Inspect for blockages: Remove and rinse the brew basket, gold-tone filter, and any removable showerhead or brew head screen. Coffee oils and grounds can restrict flow and cause overheating.
• Descale the machine: Run a full descaling cycle with a 1:1 vinegar and water solution to clear internal scale that can trap heat.

Advanced checks (if error remains):

• With the unit unplugged and bottom cover removed, inspect the heating element, thermostat, and thermal fuse mounted to the heater plate or boiler.
• Look for burnt spots, melted insulation, or a visibly blown thermal fuse.
• Test continuity of the thermal fuse and thermostat with a multimeter. Replace any open components.

If the thermal cutoff has opened due to severe overheating, it must be replaced; do not bypass it. If the unit repeatedly overheats, the control board or thermostat may be misregulating temperature and should be evaluated by a technician.