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

CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode Ref. to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>Clear Memory Mode>OPERATION , and inspection mode Ref. to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>Inspection Mode>PROCEDURE .

Use the check board when measuring the ECM terminal voltage and resistance.

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>Engine Electrical System>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

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 and engine ground.
  Connector & terminal
  
  (E162) No. 3 (+) - Engine ground (-):
Is the voltage 4.5 V or more?

Yes: Go to 2.

No: Go to 4.
CHECK HARNESS BETWEEN ECM AND FUEL PRESSURE SENSOR CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Disconnect the connector from the fuel pressure sensor.
4. Measure the resistance of harness between ECM connector and fuel pressure sensor connector.
  Connector & terminal
  
  (E159) No. 27 - (E162) No. 1:
  
  (E158) No. 6 - (E162) No. 2:
Is the resistance less than 1 Ω?

Yes: Go to 3.

No: Repair the open circuit in harness between ECM connector and fuel pressure sensor connector.
CHECK HARNESS BETWEEN ECM AND FUEL PRESSURE SENSOR CONNECTOR .
Measure the resistance between the ECM connector and engine ground.

Connector & terminal

(E158) No. 6 (+) - Engine ground:

(E159) No. 27 (+) - Engine ground:

Is the resistance 1 MΩ or more?

Yes: Replace the fuel pressure sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (EXCEPT FOR STI)>Fuel Pressure Sensor .

No: Repair the ground short circuit of harness between ECM connector and fuel pressure sensor connector.
CHECK HARNESS BETWEEN ECM AND FUEL PRESSURE SENSOR CONNECTOR .
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
  
  (E159) No. 19 - (E162) No. 3:
Is the resistance less than 1 Ω?

Yes: Go to 5.

No: Repair the open circuit in harness between ECM connector and fuel pressure sensor connector.
CHECK HARNESS BETWEEN ECM AND FUEL PRESSURE SENSOR CONNECTOR .
Measure the resistance between the ECM connector and engine ground.

Connector & terminal

(E159) No. 19 - Engine ground:

Is the resistance 1 MΩ or more?

Yes: Repair the poor contact of ECM connector.

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