Diagnostic Instructions

DTC Descriptor

DTC P0191 00: Fuel Rail Pressure (FRP) Sensor Performance

Diagnostic Fault Information

Circuit	Short to Ground	Open or High Resistance	Short to Voltage	Signal Performance
Fuel Rail Pressure (FRP) Sensor Signal	P0192 00	P0191 00 or P0193 00	P0193 00	P0191 00

Circuit/System Description

The fuel pump control module (FPCM) monitors the voltage signal from the fuel pressure sensor. This DTC will set if the FPCM detects a stuck fuel pressure sensor signal.

Conditions for Running the DTC

Conditions for Setting the DTC

Action Taken When the DTC Sets

DTC P0191 is an A type DTC.

Conditions for Clearing the DTC

DTC P0191 is an A type DTC.

Diagnostic Aids

Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Fuel System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, vary the engine speed with the accelerator pedal. Verify that DTC P0191 does not set as current.

⇒	If the DTC sets as current, test the fuel line pressure sensor signal circuit for a high resistance. If the circuit tests normal, replace the fuel line pressure sensor.

2. If the DTC does not reset in the FPCM, the system is OK. Do not replace the FPCM.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the fuel line pressure sensor.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the low reference circuit terminal 2 and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the fuel system control module.

3. Ignition ON, test for 4.8-5.2 volts between the fuel line pressure sensor 5-volt reference circuit terminal 3 and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the fuel system control module.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the fuel system control module.

4. Ignition ON, observe the Fuel Pump Control Module Fuel Rail Pressure Sensor parameter.
5. Install a 3A fused jumper wire between the 5-volt reference circuit terminal 3 and the fuel line pressure sensor signal circuit terminal 1. The scan tool should display between 4.8-5.2 volts.

⇒	If less than the specified range, test the signal circuit terminal 1 for a short to ground or an open/high resistance. If the circuit tests normal, replace the fuel system control module.

6. If all circuits test normal, replace the fuel rail pressure sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

DTC P0191 FPCM

Diagnostic Instructions

DTC Descriptor

DTC P0191: Fuel Rail Pressure (FRP) Sensor Performance

Diagnostic Fault Information

Circuit	Short to Ground	Open or High Resistance	Short to Voltage	Signal Performance
5-Volt Reference	P0641	P0641, P06A6	P0641	P06A6
Fuel Rail Pressure (FRP) Sensor Signal	P0192	P0191, P0192	P0193	P0191
Fuel Line Pressure Sensor Low Reference	--	P0641, P06A6	--	P06A6

Circuit/System Description

The fuel pressure sensor is mounted on the fuel line. Fuel pressure is measured by the fuel pressure sensor. The fuel pump flow control module (FPCM) monitors the voltage signal from the fuel pressure sensor and also supplies the voltage and the ground of the fuel pressure sensor.

Conditions for Running the DTC

Conditions for Setting the DTC

The FPCM does not detect a change in the fuel rail pressure (FRP) of at least 30 kPa (4.4 psi) when the fuel pump is operating at its minimum or maximum voltage limits for over 5 seconds.

Action Taken When the DTC Sets

DTC P0191 is an A type DTC.

Conditions for Clearing the DTC

DTC P0191 is an A type DTC.

Diagnostic Aids

Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can help determine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Fuel System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

Important: Verify that the fuel tank is not empty. Only perform this diagnostic if there is at least 2 gallons of fuel in the fuel tank. Clear the DTC, and start and run the engine. Verify that the DTC P0191 resets before proceeding with the circuit system testing. If the DTC does not reset, refer to diagnostic aids.

1. Ignition OFF, disconnect the harness connector at the fuel line pressure sensor.
2. Ignition OFF, test for less than 1.0 ohm between the low reference circuit terminal 2 and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the FPCM.

3. Ignition ON, test for 4.8-5.2 volts between the fuel line pressure sensor 5-volt reference circuit terminal 3 and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the FPCM.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the FPCM.

4. Ignition ON, observe the Fuel Pump Control Module Fuel Rail Pressure Sensor parameter.
5. Install a 3A fused jumper wire between the 5-volt reference circuit terminal 3 and the fuel line pressure sensor signal circuit terminal 1. The scan tool should display between 4.8-5.2 volts.

⇒	If less than the specified range, test the signal circuit terminal 1 for a short to ground or an open/high resistance. If the circuit tests normal, replace the FPCM.

⇒	If greater than the specified range, test the signal circuit terminal 1 for a short to voltage. If the circuit tests normal, replace the FPCM.

6. If all circuits test normal, replace the fuel pressure sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.