Air fryer will not start and displays E1 on the control panel.

Safety first: Unplug the Ultima Cosa air fryer and let it cool completely before opening any panels. Never work on a live appliance.

• Power reset: Unplug the unit for 5 minutes, then plug back in and try again. Sometimes E1 is a transient sensor read error.
• Check sensor connector: Remove the basket and drawer. On most Ultima Cosa models, the cabinet temperature sensor (NTC) is mounted near the rear or top of the cooking cavity. Access it by removing the rear cover (Phillips screws). Locate the small two-wire harness from the sensor to the main control PCB and ensure it is fully seated and not corroded.
• Inspect wiring: Look for broken, pinched, or burned wires between the NTC sensor and the control board. Repair any damaged wiring with high-temperature rated wire and proper crimp connectors.
• Test the sensor: With a multimeter set to resistance (ohms), measure across the NTC sensor leads. At room temperature, you should see a stable resistance (commonly 50–200 kΩ depending on sensor type). If the reading is infinite (open circuit) or jumps erratically when you gently move the leads, the sensor is defective and must be replaced.
• Replace the sensor: If open or out of spec, remove the mounting screw or clip, disconnect the harness, and install a compatible Ultima Cosa cabinet temperature sensor. Route the new harness away from the heating element and fan.
• Control board check: If a known-good sensor still gives E1, the main control PCB sensor input may be faulty. Inspect the board for burnt components or cracked solder joints. Replacement of the main control PCB is usually required.

If you are not comfortable using a multimeter or opening the cabinet, contact a qualified appliance technician.