Fuel Pressure Sensor
The fuel rail pressure sensor monitors and passes on the current fuel rail pressure to the ECM. The non-constant system pressure influences the position of the sensor diaphragm which alters the sensors electrical resistance.
WARNING:
A residual pressure of about 50 to 80 bar (725 to 1160 PSI) remains in the fuel rails after switching off the engine. The high-pressure system must only be opened after the fuel pressure drops to a safe level.