DTC P0191: Fuel Rail Pressure Sensor Circuit Range/Performance Bank 1: Notes

DTC detecting condition: 

Detected when two consecutive driving cycles with fault occur.

Trouble symptom: 

• Improper idling
• Poor driving performance

Wiring diagram: 

Engine Electrical System Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DATA MONITOR  .
   1. Turn the ignition switch to ON.
   2. Using the Subaru Select Monitor or a general scan tool, perform the clear memory of [Engine]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY .
   3. Turn the ignition switch to OFF.
   4. Start the engine.
   5. Using the Subaru Select Monitor, read the values in [Fuel Rail Pressure A] and [Fuel Rail Pressure B].
   NOTE: For detailed operation procedures, refer to "Common (Diagnostics)". Ref. to COMMON (DIAGNOSTICS)>DATA MONITOR .

   Is the difference of the values between [Fuel Rail Pressure A] and [Fuel Rail Pressure B] 2343 [kPa] (17577 mmHg, 692 inHg) or more?

   Yes:  Go to  2.

   No:  Refer to "Check non-permanent occurrence malfunctions". Ref. to ENGINE (DIAGNOSTICS) (H4DO)>GENERAL DESCRIPTION>INSPECTION>CHECK NON-PERMANENT OCCURRENCE MALFUNCTIONS .

2. CHECK FUEL PRESSURE SENSOR POWER SUPPLY  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from the fuel pressure sensor.
   3. Turn the ignition switch to ON.
   4. Measure the voltage between fuel pressure sensor connector and engine ground.

      Connector & terminal 

      (E68) No. 4 (+) - Engine ground (-):

   Is the voltage 4.5 - 5.5 V?

   Yes:  Go to  3.

   No:  Go to  5.

3. CHECK HARNESS BETWEEN ECM AND FUEL PRESSURE SENSOR CONNECTOR (OPEN)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from ECM.
   3. Measure the resistance of harness between ECM connector and fuel pressure sensor connector.

      Connector & terminal 

      (E53) No. 50 - (E68) No. 1:

      (E53) No. 58 - (E68) No. 2:

      (E53) No. 56 - (E68) No. 3:

   Is the resistance less than 1 Ω?

   Yes:  Go to  4.

   No:  Repair the open circuit in harness between ECM connector and fuel pressure sensor connector.

4. CHECK HARNESS BETWEEN ECM AND FUEL PRESSURE SENSOR CONNECTOR (SHORT TO GROUND)  .

   Measure the resistance between ECM connector and fuel pressure sensor connector and engine ground.

   Connector & terminal 

   (E53) No. 56 - Engine ground:

   (E53) No. 50 - Engine ground:

   Is the resistance 1 MΩ or more?

   Yes:  Replace the fuel pressure sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL PRESSURE SENSOR .

   No:  Repair the ground short circuit of harness between ECM connector and fuel pressure sensor connector.

5. CHECK HARNESS BETWEEN ECM AND FUEL PRESSURE SENSOR CONNECTOR (OPEN)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from ECM.
   3. Measure the resistance of harness between ECM connector and fuel pressure sensor connector.

      Connector & terminal 

      (E53) No. 41 - (E68) No. 4:

   Is the resistance less than 1 Ω?

   Yes:  Go to  6.

   No:  Repair the open circuit in harness between ECM connector and fuel pressure sensor connector.

6. CHECK HARNESS BETWEEN ECM AND FUEL PRESSURE SENSOR CONNECTOR (SHORT TO GROUND)  .

   Measure the resistance between ECM connector and fuel pressure sensor connector and engine ground.

   Connector & terminal 

   (E53) No. 41 - Engine ground:

   Is the resistance 1 MΩ or more?

   Yes:  Replace the fuel pressure sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>FUEL PRESSURE SENSOR .

   No:  Repair the ground short circuit of harness between ECM connector and fuel pressure sensor connector.