Check Engine Code P0191
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From: NM
DTR's 'Go to Guy'
Joined: Jan 2007
Posts: 3,811
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From: Indiana
a complete wiring diagram Refer to Section 8W.
When Monitored:
At key on.
Set Condition:
The fuel pressure sensor reading at key on does not match the expected fuel pressure reading at key on.
Possible Causes
OTHER DTC'S PRESENT
FUEL RAIL PRESSURE SENSOR
FUEL SYSTEM TAMPERING
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Diagnostic Test
1. OTHER DTC'S PRESENT
--------------------------------------------------------------------------------
With the scan tool, read DTCs.
Are any DTC's present?
Yes
Repair other DTC's first.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No
Go To2
2. FUEL PRESSURE READING
--------------------------------------------------------------------------------
Using the scan tool, monitor the actual fuel pressure reading while the key is on and engine is not running.
Is the actual fuel pressure reading greater than 870 psi?
Yes
Go To3
No
Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
3. FUEL RAIL PRESSURE SENSOR
--------------------------------------------------------------------------------
Visually inspect the fuel system components for signs of tampering, pay particular attention to the fuel pressure sensor on the fuel rail and the fuel pressure sensor wiring harness.
Were any signs of tampering discovered?
No
Replace the Fuel rail pressure sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Yes
Restore Fuel system to original condition.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
When Monitored:
At key on.
Set Condition:
The fuel pressure sensor reading at key on does not match the expected fuel pressure reading at key on.
Possible Causes
OTHER DTC'S PRESENT
FUEL RAIL PRESSURE SENSOR
FUEL SYSTEM TAMPERING
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Diagnostic Test
1. OTHER DTC'S PRESENT
--------------------------------------------------------------------------------
With the scan tool, read DTCs.
Are any DTC's present?
Yes
Repair other DTC's first.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No
Go To2
2. FUEL PRESSURE READING
--------------------------------------------------------------------------------
Using the scan tool, monitor the actual fuel pressure reading while the key is on and engine is not running.
Is the actual fuel pressure reading greater than 870 psi?
Yes
Go To3
No
Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
3. FUEL RAIL PRESSURE SENSOR
--------------------------------------------------------------------------------
Visually inspect the fuel system components for signs of tampering, pay particular attention to the fuel pressure sensor on the fuel rail and the fuel pressure sensor wiring harness.
Were any signs of tampering discovered?
No
Replace the Fuel rail pressure sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Yes
Restore Fuel system to original condition.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Banned
Joined: Jun 2004
Posts: 0
Likes: 1
From: kingston,wa
Banned
Joined: Jun 2004
Posts: 0
Likes: 1
From: kingston,wa
you're right.
mega, are there ANY fueling boxes or programmers installed on that truck?
i used to get that code when i was running an edge ez. it is from low rail pressure. went to a quad and no code.
some sensors are just barely within tolerance from the factory. there may be nothing wrong with your actual pressure, just the sensor is close to its lower tolerance range.
makes a difference if you have mods on the truck.
mega, are there ANY fueling boxes or programmers installed on that truck?
i used to get that code when i was running an edge ez. it is from low rail pressure. went to a quad and no code.
some sensors are just barely within tolerance from the factory. there may be nothing wrong with your actual pressure, just the sensor is close to its lower tolerance range.
makes a difference if you have mods on the truck.
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ptgarcia
3rd Gen Engine and Drivetrain -> 2003-2007
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Jan 15, 2007 08:46 PM
