Diagnostic Instructions

DTC Descriptors

DTC P0191: Fuel Rail Pressure (FRP) Sensor Performance

DTC P0192: Fuel Rail Pressure (FRP) Sensor Circuit Low Voltage

DTC P0193: Fuel Rail Pressure (FRP) Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
FRP Signal	P0192	P0088, P0191	P0193	P0193	--
FRP Low Reference	--	P0191	P0193	¹	--
FRP 5-Volt Reference	P0117, P0462, P0522, P0652	P0087, P0191	P0193	P0118, P0653	--
Fuel Pressure Regulator Solenoid Supply Voltage	P0088, P0090	P0088	P0090	P0087, P0191, P2510	--
¹ Opens circuit fuse or opens circuit.

Typical Scan Tool Data

Actual Fuel Rail Pressure

Circuit	Short to Ground	High Resistance	Open	Short to Voltage
Operating Conditions: The Ignition ON, with the Engine OFF Parameter Normal Range: 0.2 MPa (34.8 psi)
5-Volt Reference	0 MPa (0 psi)	Varies¹	200 MPa (29,000 psi)	0 MPa (0.0 psi)
FRP Sensor Signal	0 MPa (0 psi)	Varies¹	200 MPa (29,000 psi)	200 MPa (29,000 psi)
FRP Sensor Low Reference	--	Varies¹	200 MPa (29,000 psi)	²
Fuel Pressure Regulator Solenoid Supply Voltage	0.2 MPa (34.8 psi)¹	71 MPa (10,300 psi)¹	0.2 MPa (34.8 psi)¹	0.2 MPa (34.8 psi)¹
¹ Fuel pressure erratic ² Opens circuit fuse or opens circuit

Circuit/System Description

The fuel rail pressure (FRP) sensor has a 5-volt reference circuit, a signal circuit, and a low reference circuit. The engine control module (ECM) monitors the voltage on the FRP sensor circuits. When the fuel pressure is high, the signal voltage is high. When the fuel pressure is low, the signal voltage is low. The fuel pressure regulator has a solenoid supply voltage circuit and a solenoid control circuit. The ECM controls the fuel pressure regulator , which regulates high pressure fuel that goes to the fuel injector rails and the injectors.

Conditions for Running the DTC

P0191

P0192 and P0193

Conditions for Setting the DTC

P0191

P0192

The ECM detects the signal circuit voltage that is less than 0.254 volt for more than 1 second.

P0193

The ECM detects that the signal circuit voltage is more than 4.75 volts for more than 1 second.

Action Taken When the DTC Sets

DTC P0191, P0192, and P0193 are type A DTCs.

Conditions for Clearing the MIL/DTC

DTC P0191, P0192, and P0193 are type A DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Circuit/System Verification

Important: 

•	If you cannot duplicate the condition, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

1. Verify that DTCs P0652 or P0653 are not set.

⇒	If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

2. Observe the Actual Fuel Rail Pressure parameter with a scan tool. During engine cranking, the pressure should be at least 10 MPa. With the engine running at idle, the pressure should be close to the Desired Fuel Rail Pressure. As the engine speed increases, the Desired Fuel Rail Pressure and the Actual Fuel Rail Pressure should closely match each other.
3. Engine running, observe the DTC information with a scan tool. DTCs P0191, P0192 or P0193 should not set.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Important: Fuel pressure control will be disable if DTC P0087, P0088, P0192, or P0193 are set. Codes must be cleared to enable the device control.

P0191

1. Turn OFF the ignition.
2. Disconnect the ECM connector and the fuel pressure regulator connector.
3. Test the fuel pressure regulator solenoid supply voltage circuit for a short to voltage.
4. Disconnect the FRP sensor.
5. Test the FRP signal circuit, the 5-volt reference circuit, and the low reference circuit for high resistance.

⇒	If all circuits test normal, replace the FRP sensor.

P0192

1. Turn ON the ignition, with the engine OFF.
2. Disconnect the FRP connector and observe the Actual Fuel Pressure parameter with a scan tool.

⇒	If fuel pressure is 0 MPa (0 psi), test the FRP sensor signal circuit for a short to ground. If the circuits test normal, replace the control module.

⇒	If fuel pressure is 200 MPa (29,00 psi), replace the FRP sensor.

P0193

1. Turn ON ignition, with the engine OFF.
2. Disconnect the FRP sensor connector and probe the signal circuit with a test lamp connected to ground. The test lamp should not illuminate.

⇒	If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuits test normal, replace the control module.

3. Connect a DMM between the FRP 5-volt reference circuit and ground, and measure the voltage. The voltage should be 4.7-5.2 volts.

⇒	If the voltage is not within the specified range, test for an open in the 5-volt reference circuit. If the circuits test normal, replace the control module.

4. Connect a fused jumper between the FRP signal circuit and the low reference circuit and observe the actual fuel rail pressure parameter with a scan tool.

⇒	If fuel pressure goes to 0 MPa , replace the FRP sensor.

⇒	If fuel pressure does not go to 0 MPa, test the signal circuit and the low reference circuit for an open. If the circuits test normal, replace the control module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.