An intake air temperature sensor is a device that detects the temperature of the air after it passes through the engine air filter and before it enters the engine. Air temperature affects its density, and air density affects how much oxygen it holds. The intake air temperature sensor helps your vehicle to run well whether you are driving in subzero temperatures or through the tropics.
The engine in your vehicle needs a constant supply of both air and fuel in order to operate, and it needs them in a specific ratio. Years ago, engines were fitted with carburetors that included a lot of mechanical components that were designed to precisely meter the air and fuel but were prone to malfunction. And carburetors were not very good at adjusting the air to fuel ratio to accommodate varying conditions, such as ambient temperature swings or changes in altitude.
Instead, vehicles built since the mid 1990s have featured electronic fuel injection, or EFI. Relying on fuel injectors to atomize fuel inside the combustion chambers, EFI goes far beyond the capabilities of a carbureted engine. This system uses the engine’s main computer, the Engine Control Module, or ECM - alternatively known as an Engine Control Unit (ECU) or Powertrain Control Module (PCM) - to control the ratio of air to fuel injected in the engine. Data received from an array of engine sensors is continuously monitored and analyzed by the ECM so that changes can be made no matter what the driving conditions might be. One of those sensors is the intake air temperature sensor.