Installed on the front-end module, the Ambient Temperature Sensor (ATS) senses the ambient temperature. ECM receives not only the intake air temperature but also the ambient air temperature values at the same time to precisely control the intake air amount provided through the turbo charger. The electrical resistance of the thermistor decreases as the temperature increases, and vice versa. This sensor has a Negative Temperature Coefficient (NTC) whose resistance is in inverse proportion to the temperature.