P0191

Documented for: 2.0D; 2.5L/3.0L gasoline · System(s): EMS/diesel, EMS OBD II · Factory MIL flag: 2 · Default action: ECM Default: –Default value of 3.80 BAR (55.11 psi) used –Fuel pump feedback control inhibited

Common causes

• Faulty inlet/rail pressure sensor
• wiring
• implausible pressure
• fuel-system fault
• Fuel filter / system restriction Fuel system leak Incorrect fuel pump output IP Sensor to ECM sensing circuit: high resistance, open circuit, short circuit to ground, short circuit to high voltage IP Sensor to splice sensor supply circuit: high resistance, open circuit IP Sensor to splice sensor ground circuit: high resistance, open circuit, short circuit to ground, short circuit to high voltage IP Sensor failure

Quick checks

• Confirm freeze-frame and conditions when the code set
• Inspect connectors, grounds, and harness for the circuit named in the code
• Compare live sensor values vs expected (unplugged/biased sensors are common)
• Check intake boots, PCV, and vacuum lines for splits (very common on aged X-Types)

Typical fixes

• Verify actual vs commanded rail pressure, sensor wiring and fuel supply
• replace the failed component only after testing.