DTC P1191: Fuel Rail Pressure Sensor "A" Circuit No Activity Detected: 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 Refer to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>CLEAR MEMORY MODE>OPERATION , and inspection mode Refer 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 Refer to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

CHECK CURRENT DATA.
1. Start the engine.
2. Read the value of «Fuel Rail Pressure A» using the Subaru Select Monitor or a general scan tool.
NOTE:
- Subaru Select Monitor
  For detailed operation procedures, refer to "Current Data Display For Engine". Refer to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>SUBARU SELECT MONITOR .
- General scan tool
For detailed operation procedures, refer to the general scan tool operation instructions.
Is the value of «Fuel Rail Pressure A» 2500 kPa (25.49 kgf/cm2, 362.6 psi) or more?

Yes: Go to 2.

No: Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
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
  
  (E162) No. 3 (+) - Engine ground (-):
Is the voltage 4.5 V or more?

Yes: Go to 3.

No: Go to 6.
CHECK FUEL PRESSURE SENSOR SIGNAL.
1. Connect all connectors.
2. Start the engine.
3. Read the value of «Fuel Rail Pressure A» when idling using the Subaru Select Monitor or a general scan tool.
  NOTE:
  - Subaru Select Monitor
    For detailed operation procedures, refer to "Current Data Display For Engine". Refer to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>SUBARU SELECT MONITOR .
  - General scan tool
  For detailed operation procedures, refer to the general scan tool operation instructions.
4. Measure the voltage between ECM connectors.
  Connector & terminal
  
  (E158) No. 6 (+) - (E159) No. 27 (-):
When the value of «Fuel Rail Pressure A» during idling is approx. 4, 000 kPa (40.79 kgf/cm² , 580.2 psi), is the voltage 0.75 - 1.5 V?

Yes: Repair the poor contact of ECM connector.

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 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

(E158) No. 6 - Engine ground:

(E159) No. 27 - Engine ground:

Is the resistance 1 MΩ or more?

Yes: Replace the fuel pressure sensor. Refer to FUEL INJECTION (FUEL SYSTEMS) (EXCEPT FOR STI)>FUEL PRESSURE SENSOR .

No: Go to 6.
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 7.

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.