Sensors
Sensor and thermal fuse
De'Longhi gives owners no repair jobs. The manual: "If the appliance is faulty, do not attempt to repair. Turn it off, unplug from the mains socket and contact Customer Services." The US manual adds that removing the exterior, repairing or modifying the machine voids the warranty (1 year in the US plus 1 with registration; 2 years in the UK and EU). Treat this as Customer Services work: the methods shown are owners', named where they appear.
"All lights flash" means the heating circuit is not working: a cut-out, the thermoblock or a wire, or overheating after heavy steam use (Coffee Grump). De'Longhi: unplug and contact Customer Services. Owners let it cool for about 30 minutes and try again.
The thermal fuse is a one-shot part: once it has blown it must be replaced. A service check tests it and the heater for continuity with the machine unplugged. The sensor's resistance is not published.