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P0191 issue

48K views 20 replies 6 participants last post by  Tompeckrtp 
#1 ·
hey everybody im getting a P0191 (Fuel Rail Pressure Sensor Circut Range/Performance) DTC when i shift into park after driving. Doesnt happen when driving or when i lay into it, only after putting it into park right before i shut her down. i was leaning towards needing a lift pump but data loging on the mini max shows no sign of low pressure even on performance tune. runs great, no bogging or lack of power. also it happens on any tune, stock thru performance. mods are mini max all deletes, everything else is stock. any ideas out there? Thanks in advance for any help!
 
#2 ·
Here is a possible solution to your issue. Not sure it will work, but sounded like what you described. :)
 
#3 ·
I'm still getting the same code. I got a lift pump and thought it would fix it but it didn't. Running the tow tune and still get the code. I'm think its the pressure regulator or a wiring issue. I'm taking it to the local mechanic shop friday to see what he can find

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#4 ·
Thanks chevytuff, Oobree Let Me Know What They Find, Im Going To Order A New Rail Pressure Sensor And Give That A ShotIll Keep You Updated On Results.
 
#5 ·
Thanks. I sure hope he finds the problem i'm tired of the engine light.
Does your truck start up normally??

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#6 ·
ya It Starts Fine Except For The Remote Start Untill I Clear The Code, Changed My Oil Right Before This Started And Have Bad Typewritter Tick (My First Change Since Ive Had It) But I Belive Thats unrelated What Tuneing Do You Have?
 
#7 ·
Mine starts good to just takes an extra 2 seconds for it to start than it should
I have the h&s mini max

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#8 ·
did the mechanic ever find anything? im still waiting for my sensor to show up?
 
#9 · (Edited)
Didn't have time to take it there friday. To busy with work
 
#11 ·
No, Ive Got The New Sensor Just Havent Had Time To Put It In Yet, Been Pretty Swamped With Work. Im Gonna Try To Get It Done By The End Of The Week. Do You Know If The Sensor Is On The Passenger Or Driver Side Rail? IVe Till Got Alot To Learn About The LML haha
 
#12 ·
Ha ha. I don't know much either but it is on the drivers side
 
#14 ·
Thanks!
 
#15 ·
I Just Got The New Rail Pressure Sensor installed I'll Update Tomorrow If Cured The CEL
 
#16 ·
No Luck With The New Sensor, Its Still Throwing P0191 At me
 
#17 ·
DTC P0191

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
Review Strategy Based Diagnosis (See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Strategy Based Diagnosis) for an overview of the diagnostic approach.
Diagnostic Procedure Instructions (See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0191
Fuel Rail Pressure (FRP) Sensor Performance
Diagnostic Fault Information




Typical Scan Tool Data




Circuit/System Description

Idle Mode

During certain engine operating modes the engine control module (ECM) calculates an adaptation factor to align the fuel pressure regulator 2 set point with the measured fuel rail pressure. This is done to adjust for manufacturing tolerances and aging of components. If the ECM calculates an adaptation factor outside the minimum or maximum calibrated limits, DTC P0191 is set.

Post Drive Mode

During post-drive mode, the fuel pressure regulator 2 relieves any remaining fuel pressure from the rails. After a 30 second bleed-down, the fuel rail pressure sensor should read atmospheric pressure and return the proper signal voltage to the ECM. If the signal voltage is outside of the specified limits, DTC P0191 is set.

Conditions for Running the DTC

Idle Mode
Fuel level is greater than 15 %.
DTC P0016, P0117, P0118, P0192, P0193, P0335, P0336, P0340, or P0341 is not set.
Engine has run above 2000 RPM for 15 s during current key cycle.
Fuel pressure control is in fuel pressure regulator 2 mode or in combined pressure control mode.
Post Drive Mode
Fuel level is greater than 15 %.
DTCs P0016, P0117, P0118, P0192, P0193, P0335, P0336, P0340, or P0341 are not set.
Fuel Temperature is greater than 0°C (32°F).
Fuel pressure regulator 2 current is less than 1.71 A.
Engine OFF time is greater than 30 s.
Fault condition exists for more than 30 s.
Conditions for Setting the DTC

Idle Mode
The ECM detects a drifted fuel rail pressure value by determining the adaptation factor of the fuel rail pressure regulator 2.
The fuel pressure regulator 2 adaptation factor is outside the ECM's correction limits.
Post Drive Mode
The fuel rail pressure sensor voltage is not between 0.352 V and 0.65 V.
The fault condition exists for more than 30 s.
Action Taken When the DTC Sets

DTC P0191 is a Type A DTC.
If Post Drive Mode fails, engine will go to Reduced Power Mode
Conditions for Clearing the MIL/DTC

DTC P0191 is a Type A DTC.

Diagnostic Aids

Review the freeze frame data to determine if the engine was running when the DTC set.
Connector terminal fretting or poor connections of the wiring harness may cause this DTC to set.
Contaminated fuel may cause this DTC to set.
Reference Information
Schematic Reference

Engine Controls Schematics (See: Diagrams\Electrical\Powertrain Management\System Diagram)
Connector End View Reference

Component Connector End Views (See: Diagrams\Connector Views\Connector End Views By Name)
Description and Operation

Fuel System Description (See: Powertrain Management\Computers and Control Systems\Description and Operation\Fuel System Description)
Electrical Information Reference

Circuit Testing (See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Circuit Testing\Circuit Testing)
Connector Repairs (See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Connector Repairs\Connector Repairs)
Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Circuit Testing\Testing for Intermittent Conditions and Poor Connections)
Wiring Repairs (See: Testing and Inspection\Component Tests and General Diagnostics\General Electrical Diagnostic Procedures\Wiring Repairs\Wiring Repairs)
DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions\Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (See: Testing and Inspection\Programming and Relearning\Control Module References) for scan tool information

Circuit/System Verification

Ignition ON, observe the DTC information with a scan tool. Verify no other DTCs are set.
¤If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions\Diagnostic Trouble Code (DTC) List - Vehicle) for further diagnosis.
Engine at idle, the Actual Fuel Rail Pressure should be close to the Desired Fuel Rail Pressure.
Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing

Note:
You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
Review Freeze Frame Data to determine which operating mode the DTC was set.
Ignition OFF, open a fuel injector high pressure fuel line.
Ignition ON, verify the scan tool Fuel Pressure Sensor Voltage parameter is between 0.352-0.65 V.
¤If less than the specified range, test the Fuel Rail Pressure Sensor Signal circuit and the Fuel Rail Pressure Sensor 5 Volt Reference circuit for high resistance. If the circuit tests normal, replace the B47B fuel rail pressure sensor.
¤If greater than the specified range, test Fuel Rail Pressure Sensor Low Reference circuit for high resistance. If the circuit tests normal, replace the B47B fuel rail pressure sensor.
Install the fuel injector high pressure line.
Engine running, observe the scan tool Fuel Pressure Sensor Voltage parameter is less than 0.65 V within 30 seconds after ignition OFF.
¤If the Fuel Pressure Voltage parameter is greater than the specified value, replace the Q18B fuel pressure regulator 2.
Engine at idle, command the fuel pressure incrementally through the entire fuel pressure range with a scan tool. The Actual Fuel Rail Pressure and the Desired Fuel Rail Pressure should be within 690 kPa (100 psi) for the entire fuel pressure range.
¤If not within the specified range, replace the Q18B fuel pressure regulator 2.
¤If the system tests normal, refer to Diagnostic Aids.
Repair Instructions

Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.

Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement (See: Powertrain Management\Fuel Delivery and Air Induction\Fuel Pressure Sensor/Switch\Service and Repair\Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement)
Fuel Pressure Relief Valve Replacement (See: Engine, Cooling and Exhaust\Engine\Fuel Pressure Release\Service and Repair)
Control Module References (See: Testing and Inspection\Programming and Relearning\Control Module References) for ECM replacement, programming, and setup.



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#19 ·
Any updates on this? My 11 LML started throwing this code since its gotten very cold outside. Runs fine but throws at idle after driving
 
#20 ·
I replaced The pressure Sensor And Nothing Changed. Mine will Still Trip The CEL Here And There But I Just Clear It And Move Along. I Don't Think Its Anything To Be Concerned About.
 
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