Smeg oven will not heat, display shows Er01 shortly after turning a cooking function on.

Safety first: Disconnect the oven from mains power at the breaker before removing any panels. Allow the oven to cool completely.

• Access the temperature probe: Open the oven door and locate the temperature sensor (NTC probe) at the rear wall (usually top-left or top-center inside the cavity). It is a small metal rod held by 1–2 screws.
• Check for obvious damage: Inspect the probe for burns, deformation, or broken insulation. If damaged, replace the probe with a genuine Smeg NTC temperature sensor.
• Test the sensor: Remove the mounting screws, gently pull the probe forward, and disconnect the connector. Using a multimeter set to resistance (ohms), measure across the two terminals. At room temperature, most Smeg NTC sensors read roughly 500–1100 Ω (check service data if available). An open circuit (OL) or 0 Ω indicates a faulty sensor.
• Inspect wiring: Trace the sensor cable to the main control board behind the top or rear panel. Look for pinched, burnt, or broken wires and loose connectors. Reseat the connector on the control board.
• Reset and test: Reconnect power, clear the error by switching the oven off at the knob or breaker for 2–3 minutes, then select a low-temperature bake function. If Er01 returns with a known-good sensor and wiring, the main control board temperature input is likely defective and should be replaced by a qualified technician.