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

WARNING: This page is about a different variant/trim than selected.

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 (IMPREZA MODEL)>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM .

IMPREZA MODEL

Courtesy of SUBARU OF AMERICA, INC.

CROSSTREK MODEL

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0 (EXCEPT FOR HEV))>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE CHECK BOARD .

NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0 (EXCEPT FOR HEV))>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

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 (DIAG)>CLEAR MEMORY .
3. Turn the ignition switch to OFF.
4. Start the engine.
5. Using the Subaru Select Monitor or a general scan tool, read the values of [Fuel Rail Pressure A] and [Fuel Rail Pressure B].
  NOTE: For detailed operation procedures, refer to "Common (Diagnostics)". Ref. to COMMON (DIAG)>DATA MONITOR .
Is the difference of the values between [Fuel Rail Pressure A] and [Fuel Rail Pressure B] 2183 kPa (16377 mmHg, 645 inHg) or more?

Yes: Go to 2.

No: Refer to "Check non-permanent occurrence malfunctions". Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0 (EXCEPT FOR HEV))>GENERAL DESCRIPTION>INSPECTION>CHECK NON-PERMANENT OCCURRENCE MALFUNCTIONS .
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 and terminal
  
  (E162) No. 4 (+) - Engine ground (-):
Is the voltage 4.5 - 5.5 V?

Yes: Go to 3.

No: Go to 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 and terminal
  
  (E158) No. 50 - (E162) No. 1:
  
  (E158) No. 58 - (E162) No. 2:
  
  (E158) No. 56 - (E162) 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.
CHECK HARNESS BETWEEN ECM AND FUEL PRESSURE SENSOR CONNECTOR (SHORT TO GROUND) .
Measure the resistance between the ECM connector and engine ground.

Connector and terminal

(E158) No. 50 - Engine ground:

(E158) No. 56 - Engine ground:

Is the resistance 1 MΩ or more?

Yes: Replace the fuel pressure sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>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 (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 and terminal
  
  (E158) No. 41 - (E162) 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.
CHECK HARNESS BETWEEN ECM AND FUEL PRESSURE SENSOR CONNECTOR (SHORT TO GROUND) .
Measure the resistance between the ECM connector and engine ground.

Connector and terminal

(E158) No. 41 - Engine ground:

Is the resistance 1 MΩ or more?

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

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