After cooking timer counts down to zero, the pressure built up inside the Pressure Rice Cooker is necessary for final stages of cooking. Food may be undercooked if the pressure relief valve is not properly locked during cooking or if the user manually exhausts pressure too soon after cooking. If excessive steam escapes from the lid during the process, it indicates a failure to pressurize properly, likely due to an unlocked valve or a displaced/damaged sealing ring. If the cooker cannot contain pressure and the problem persists, please replace the sealing ring or lid, or send the cooker to Customer Service for examination.