The intake air temperature sensor is a clever electronic sensor which measures the temperature of the air travelling into the engine. The intake air temperature sensor has an important part to play in the performance, power and efficiency of the car's engine.

The engine needs the correct amount of air and fuel flowing through it in order for the fuel to burn in the cylinders and for the engine to ignite or spark at the right time. If the ignition sparks at the wrong time, there will be less power in the engine and it will try to make up for this by using more fuel, significantly reducing fuel efficiency, which in turn increases the car's CO2 emissions. If combustion occurs too soon this can also cause significant damage to various engine components. The colder the air entering the intake, the denser it is. Therefore, the colder the air is, the higher the ratio of fuel that is needed to ensure the air and fuel mixture is correct in order for combustion to occur at the right point. The intake air temperature sensor detects the temperature of the air and sends this information to the car's ECU (Engine Control Unit) which uses these measurements, along with information provided by the air flow mass sensor (which measures air flow; the mass of air which is flowing through the car's engine), to control the amount of fuel flowing into the engine at the point at which the ignition sparks. 

Normally located in the intake manifold, where the air is entering the vehicle, the intake air temperature sensor is either a separate sensor or part of the air flow mass sensor.

Prone to a build-up of dirt, oil and other unwanted deposits, the intake air temperature sensor can get clogged up over time.  When this happens, the performance of the engine is likely to be affected and engine emissions will be higher. A fault in the intake air temperature sensor will cause the Check Engine light to show on the dashboard. A broken intake air temperature sensor can sometimes prevent a car from idling properly (the ability for a car's engine to run while it is not moving) and may cause the engine to splutter and stall. If there is a fault in the intake air temperature sensor a replacement intake air temperature sensor is the ideal compatible replacement part.