Display shows E05, machine does not heat water and remains cold.

Safety first: Unplug the coffee maker and allow at least 30 minutes for internal components to cool. Heating circuits carry mains voltage—if you are not experienced, contact a technician.

Steps:

• Power reset: Disconnect from mains for 10 minutes, then reconnect and test. If E05 returns immediately, proceed.
• Access the boiler/thermoblock: Remove the top or side cover. Locate the aluminum thermoblock or boiler assembly with two thick heater wires.
• Inspect wiring: Look for burnt connectors, discolored insulation, or loose spade terminals. Reseat any loose connectors firmly.
• Check thermal fuse and thermostat: Many Tefal models use a thermal fuse and/or manual-reset thermostat clipped to the boiler. Inspect for signs of overheating. A blown thermal fuse will require replacement; do not bypass it.
• Resistance test (advanced): With the unit unplugged and heater wires disconnected, measure resistance across the heating element. A typical value is 20–60 Ω. An open circuit indicates a failed heater.
• Resettable thermostat: If your model has a manual-reset thermostat (small button on a disc), press it gently to reset. If it clicks, it was tripped due to overheating; investigate descaling and ventilation issues.
• Reassemble and test: After any corrections, reassemble covers and test. Persistent E05 usually means the heater or thermal fuse assembly must be replaced. If you are unsure, seek professional service.