A throttle position sensor is an electronic device that monitors the position of the engine throttle in your vehicle.
In order for an internal combustion engine to operate, it needs a specific mixture of air and fuel fed into the combustion chambers. On a modern engine, that is the job of a tube-shaped housing mounted on top of the engine called the throttle body. It is part of the air intake system. Inside the throttle body is a butterfly valve, a flat metal plate that opens and closes to allow varying amounts of air into the engine. When the plate is closed, the throttle body prevents air from entering your engine. When it is open, air enters and mixes with fuel to be injected into the cylinders. The more air and fuel, the more power.
But the mixture between the air and fuel must be in specific proportions, and the amounts of each must accommodate engine performance across a wide range of conditions. The throttle position sensor measures the degree to which the throttle valve is open and sends that information to the Engine Control Module (ECM) that controls engine operation. Besides monitoring the amount of air entering your engine, the data also informs other operations, such as fuel amount, ignition and camshaft timing, and more, so that your engine will run as efficiently as possible.