A method for determining ambient air temperature outside of a vehicle with a sensor mounted on the vehicle, comprising the steps of: monitoring a vehicle parameter ; comparing a value of the vehicle parameter relative to a reference value , and responsive thereto, controlling a device for moving ambient air across a sensor mounted on the vehicle to measure ambient air temperature, the ambient air being drawn from outside the vehicle; and, taking a reading of ambient air temperature with the sensor , the method being characterized in that the vehicle parameter is a vehicle road speed and the reference value is a reference road speed value, the method comprising activating the device for moving ambient air if the monitored road speed is below the reference road speed value, and if the determined road speed is above the stored road speed value for at least a predetermined time duration, comprising not activating the device and continuously taking temperature readings as the ambient air temperature, or the method being alternatively characterized in that the vehicle parameter is engine temperature and the reference parameter value is a reference engine temperature value, the method comprising the steps of: determining that an engine temperature is above the reference engine temperature value; holding the last held temperature reading as the ambient air temperature for a measured interval; wherein the step of controlling the device for moving ambient air comprises activating the device to move ambient air across the sensor after the measured interval; taking a temperature reading with the sensor ; and, determining the temperature reading as the ambient air temperature if the temperature reading is lower than the held temperature value. monitoring a vehicle parameter ; comparing a value of the vehicle parameter relative to a reference value , and responsive thereto, controlling a device for moving ambient air across a sensor mounted on the vehicle to measure ambient air temperature, the ambient air being drawn from outside the vehicle; and, taking a reading of ambient air temperature with the sensor , the method being characterized in that the vehicle parameter is a vehicle road speed and the reference value is a reference road speed value, the method comprising activating the device for moving ambient air if the monitored road speed is below the reference road speed value, and if the determined road speed is above the stored road speed value for at least a predetermined time duration, comprising not activating the device and continuously taking temperature readings as the ambient air temperature, or the method being alternatively characterized in that the vehicle parameter is engine temperature and the reference parameter value is a reference engine temperature value, the method comprising the steps of: determining that an engine temperature is above the reference engine temperature value; holding the last held temperature reading as the ambient air temperature for a measured interval; wherein the step of controlling the device for moving ambient air comprises activating the device to move ambient air across the sensor after the measured interval; taking a temperature reading with the sensor ; and, determining the temperature reading as the ambient air temperature if the temperature reading is lower than the held temperature value. determining that an engine temperature is above the reference engine temperature value; holding the last held temperature reading as the ambient air temperature for a measured interval; wherein the step of controlling the device for moving ambient air comprises activating the device to move ambient air across the sensor after the measured interval; taking a temperature reading with the sensor ; and, determining the temperature reading as the ambient air temperature if the temperature reading is lower than the held temperature value. <EOS>