Air fryer displays E12 and cannot reach set temperature; preheat never completes.

Safety first: Unplug the unit and allow it to cool before accessing internal components.

Steps to troubleshoot E12:

• 1. Verify with external thermometer: Run the air fryer at a known temperature (e.g., 400°F/200°C) and measure actual temperature inside the basket with an oven thermometer. If actual temperature is far off, a sensor or control issue is likely.
• 2. Inspect sensor mounting: Access the NTC sensor and ensure it is firmly attached to the metal of the cooking chamber or bracket as designed. Loose sensors can read incorrectly.
• 3. Check sensor wiring: Look for corrosion or loose connections at the sensor plug on the main board.
• 4. Replace NTC sensor: If readings are unstable or far from expected values at room temperature, install a new Insignia-compatible NTC sensor.
• 5. Control board replacement: If a new sensor does not resolve E12 and the unit still misreads temperature, the analog-to-digital converter or firmware calibration on the main board may be faulty. Replace the main control board.

Warning: Incorrect temperature control can lead to undercooked food or overheating; do not ignore persistent E12 errors.