The FRP sensor measures the pressure of the fuel near the fuel injectors. This signal is used by the ECM to adjust the fuel injector pulse width and meter fuel to each combustion cylinder. The Fuel Rail Pressure (FRP) sensor is a diaphragm strain gauge device in which resistance changes with pressure.

The electrical resistance of a strain gauge increases as pressure increases, and the resistance decreases as the pressure decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signal to the Engine Control Module (ECM) corresponding to pressure.