The term "injector bar sensor" refers to the Fuel Rail Pressure Sensor. The "injector bar" is the mechanics' slang term for the fuel rail, which sits directly on top of the fuel injectors and supplies them with fuel.
Where It Is and What It Does
Location: It is a 3-pin sensor threaded directly into the high-pressure fuel rail (the metal bar feeding the fuel injectors).
Function: It monitors real-time fuel pressure inside the rail so the engine computer can properly adjust fuel delivery.