What is the sensor on 2009 Toyota Corolla air filter housing?

Although I have not personally seen this sensor, the only sensors that are usually in the intake are MAF sensors MAP sensors and IAT sensors. MAF sensors are usually a whole section of pipe and when you look through them you'll see a screen with bars that run across the diameter of the pipe. These sensors tell the car how much air is flowing through the intake. IAT sensors are usually small sensors that plug into a grommet in the intake that have a guard around them. These tell the computer what the temperature is of the incoming air so the car can adjust the air/fuel ratio accordingly. IAT sensors work in conjunction with MAP sensors. MAP sensors tell the car what the pressure is of the air that is coming in, when the computer compares this reading with that of the IAT it can calculate how dense the air is in order to adjust the air/fuel mixture. If I were to take a guess I would say its the IAT sensor.