DTC P0091-00: Fuel Pressure Regulator 1 Control Circuit Low: General Description

GDI PCM operates fuel pressure control valve with the signal from fuel rail pressure sensor to control optimized RPM and rail pressure. But PCM shows this DTC and enters limp home mode limiting fuel mass and maximum RPM in order to prevent abnormal control of PCM under the bad condition out of target rail pressure range.

Rail pressure monitoring error DTC shows indirectly the status of low pressure fuel and mechanical operating status of high pressure pump and fuel pressure regulator with the signal of rail pressure sensor and fuel pressure regulator.