Faulty fuel pump
Fuel line restricted
Faulty fuel pressure sensor
Fuel pressure sensor harness is open or shorted
Fuel pressure sensor electrical circuit poor connection
Faulty fuel pressure regulator
Engine Light ON (or Service Engine Soon Warning Light)
The Engine Control Module (ECM) uses commanded fuel pump flow to determine a desired fuel rail pressure. The actual fuel pressure is monitored using the Fuel Rail Pressure (FRP) Sensor.