My wife just came home and said the frost warning had gone off on the car and the air temp in the dash was reading -25Deg C. I have looked at the front of the car, and the sensor is in tact and I can not see any damage around the area. I know this is England, but todays temperature was well over 25 Deg C, (very hot ) so why is this sensor reading Minus 25?

Is this a faulty sensor, or is it more serious?

Cheers Joe