E02 appears on the display and the machine stops during preheating or does not heat at all.

Safety first: Unplug the coffee maker and let it cool for at least 30 minutes. Hot internal parts can cause burns.

• Power cycle: Disconnect power for 5 minutes, then plug back in and try again. Temporary electronic glitches can trigger E02.
• Check for overheating signs: Smell for burnt odors or look for discoloration around the boiler area (if accessible from a service panel). If you notice burning, do not use the machine.
• Clean ventilation: Ensure the machine has at least 10 cm clearance around it and that ventilation slots are not blocked by cabinets or walls. Overheating can stress the NTC sensor.
• User-accessible reset (if present): Some Ariete models have a thermal safety reset button on the base or rear. With the unit unplugged, press the small red or black button until it clicks, then reconnect power.
• If E02 remains: The NTC probe on the boiler or its wiring is likely defective and must be tested with a multimeter and replaced. This requires opening the machine and should be done by a qualified technician.