Display shows F13 and the auxiliary oven or grill does not heat.

Safety first: Disconnect mains power before accessing the oven rear or internal panels.

• Identify the cavity: Determine whether the fault relates to the secondary oven or grill section based on the model and which functions fail.
• Locate the sensor: In the affected cavity, find the temperature sensor probe at the rear wall. Remove its mounting screws and gently pull it forward to access the connector.
• Test resistance: Disconnect the sensor and measure its resistance at room temperature. Compare to the main oven sensor specification; a large deviation, open circuit, or near-zero reading indicates a faulty sensor.
• Inspect wiring: Remove the rear panel and trace the sensor wires to the control board. Look for pinched, burnt, or disconnected wires.
• Replace sensor: Install a new DeLonghi-compatible auxiliary oven temperature sensor if the original is defective. If the sensor and wiring are good but F13 remains, the control board input for that sensor may be faulty and require board replacement.