The note documents briefly work done on a newly developed sensor for making fast temperature measurements on the air flow in the intake ports of an SI engine and in the EGR input line. The work reviewed has been carried out in close cooperation with Civ. Ing. Michael Føns, the author (IAU) and Spencer C. Sorenson (ET). The theory which decribes in detail the overall dynamic chracteristics of the sensor was developed at IAU, DTU.