Machine stops during heating phase, display shows E02 and no coffee is dispensed.

Safety first: Disconnect the appliance from mains power and allow at least 30 minutes for internal components to cool before opening any covers.

Step-by-step:

• 1. Power reset: Unplug the machine for 5 minutes, then reconnect and try again. Transient sensor errors sometimes clear after a full power cycle.
• 2. Descale the machine: Run a full Siemens-approved descaling program using the recommended descaling agent. Heavy scale on the thermoblock can cause localized overheating and trigger E02.
• 3. Check ventilation: Ensure the coffee machine has adequate space around it (especially at the rear and sides) so heat can dissipate. Overheating due to poor ventilation can aggravate sensor readings.
• 4. Inspect NTC connection (advanced): With the top cover removed, locate the thermoblock assembly and its small NTC sensor (usually clipped or screwed to the block with two thin wires). Check that the connector is fully seated on the control board and that the wires are not pinched or broken.
• 5. Professional diagnosis: If E02 recurs after descaling and visual checks, the NTC sensor or control board is likely defective. These parts should be tested and replaced by a qualified Siemens technician.