P0191

Read the instructions below then start the fault diagnostic procedure.

Symptom: CHECK ENGINE. Loss of performance.

P0191

Fault symptom

•	CHECK ENGINE.

•	Loss of performance.

On-Board Diagnostics

Type of diagnosis:

-	Continuous.

Enable criteria:

The following conditions must be fulfilled when the engine is started:

-	Engine speed between 50-300 rpm.

-	Fuel pressure greater than 15 MPa.

-	>5 mm 3 /combustion.

-	DTCs P0192, P0193, P1636, P1637 not active.

The following conditions must be fulfilled when the engine is running:

-	Engine speed greater than 500 rpm.

-	Fuel pressure greater than 15 MPa.

-	Fuel quantity >5 mm 3 /combustion.

-	Fuel temperature lower than 110 °C.

-	Pump compensation value should not exceed 140 Ca.

-	DTCs P0192, P0193, P1636, P1637 not active.

Fault criteria:

-	The difference between actual fuel pressure and desired fuel pressure is more than 20 MPa and the change in voltage across the sensor between two measurements falls below a transition of 80 mV when the control module requests an increase/decrease in pressure.

Dependents:

-	P0181, P0183, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277, P1200, P0200, P0216, P0255, P0254, P0258, P0259

System reaction to a fault:

-	Substitute value for fuel pressure is equal to the calculated value. The following limitations apply: Pedal position sensor adjustable to max 30 %, fuel quantity max 20 mm 3 /combustion, fuel rail pressure max 40 MPa, idling speed set to 1000 rpm and EGR control switched off.

OK report:

-	Fault criteria not fulfilled.

Fault handling: (See section Fault handling III, other emissions-related components and functions for more information)

-

Type III.

Diagnostic help

Fault diagnosis concerns an electrical fault in connecting leads or in the sensor.

Functions in the diagnostic tool related to the fault:

-	Read value: Target Fuel Pressure, Fuel Pressure ( Fuel Pressure Sensor)

See also description of read value under "Read Values" menu for more information.