In a small bowl mix the sweet potato cubes and the oil. Season with salt and pepper.
Heat the cubes in the air fryer at 400 degrees F for 12-14 minutes. At the 6 minute mark, remove the basket and shake to help stir the sweet potatoes. Then place basket back into air fryer and resume heating.
Be sure not to add any extra moisture (water or oil) to the sweet potato cubes, it will encourage them to burn quicker. If this is your first time cooking, I would check the cubes at the 10 minute mark. Each air fryer can vary a bit.