Coffee maker stops during preheat, display shows E02 and no water is dispensed.

Safety first: Unplug the coffee maker and allow it to cool completely before opening any covers. Hot boiler components can cause burns.

Steps:

• Power reset: Disconnect the machine from mains for 5–10 minutes to clear any transient error. Reconnect and test. If E02 returns immediately, continue.
• Access the thermistor: Remove the top or rear cover (depending on your Tefal model) by undoing the screws. Locate the aluminum boiler or thermoblock; the thermistor is usually a small probe or sensor clipped or screwed to it with two thin wires.
• Check connections: Inspect the thermistor plug where it connects to the main PCB. Reseat the connector and clean any visible oxidation with contact cleaner and a cotton swab.
• Visual inspection: Look for damaged insulation, pinched wires, or signs of overheating around the thermistor and boiler. If the sensor body is cracked or burnt, it must be replaced.
• Basic resistance check (for advanced users): With the unit unplugged and the thermistor disconnected, measure its resistance using a multimeter. At room temperature, most Tefal NTC thermistors will read between 50–150 kΩ (exact value depends on model). An open circuit (OL) or 0 Ω indicates a failed sensor.
• Reassemble and test: If wiring and sensor look intact, reassemble the covers, plug in, and test. Persistent E02 after these checks usually means the thermistor or the control board is defective. Replace the thermistor first; if the error remains, seek professional diagnosis of the PCB.