Ford ITPMS Technology (Individual Tire Pressure Monitoring System) constantly monitors the pressure in all four Vehicles tires and informs you if any are significantly below of the ideal pressure level.
The Tire Pressure Monitoring System has sensors mounted on the valve stems that measure the pressure in each tire and thus automatically transmit a warning to your Ford Vehicle's instrument panel, in the event that any of the tires If there is a significant level of low pressure, if this happens it is important to check the pressure and calibrate the tire at the correct level.
Please note that if the ITPMS is not working properly if you are using a spare tire then the low tire pressure light will flash then stay on.