Diagnostic Instructions

DTC Descriptors

DTC P0091: Fuel Pressure Regulator Solenoid Control Circuit Low Voltage

DTC P0092: Fuel Pressure Regulator Solenoid Control Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open	Short to Voltage
Fuel Rail Pressure Sensor 5-Volt Reference Circuit	P0192, P0642	P0192	--
Fuel Rail Pressure Sensor Signal Circuit 1	P0192	P0193	P0193
Fuel Rail Pressure Sensor Signal Circuit 2	P0192	P0193	P0193
Fuel Rail Pressure Sensor Signal Circuit 1 and 2	P0192	P0193	P0193
Fuel Rail Pressure Sensor Ground Circuit	--	P0193	--

Typical Scan Tool Data

Actual Fuel Rail Pressure

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running Parameter Normal Range: 25 MPa
Fuel Rail Pressure Sensor 5-Volt Reference Circuit	0.0 MPa	0.0 MPa	--
Fuel Rail Pressure Sensor Signal Circuit 1	0.0 MPa	246.6 MPa	246.6 MPa
Fuel Rail Pressure Sensor Signal Circuit 2	0.0 MPa	246.6 MPa	246.6 MPa
Fuel Rail Pressure Sensor Signal Circuit 1 and 2	0.0 MPa	246.6 MPa	246.6 MPa
Fuel Rail Pressure Sensor Ground Circuit	--	246.6 MPa	--

Circuit/System Description

The fuel rail pressure (FRP) regulator is installed to the fuel supply pump and controls the suction fuel quantity into the fuel rail. The FRP regulator is fully opened in the normal state and larger drive current results in smaller opening. The engine control module (ECM) calculates desired fuel rail pressure and fuel flow rate and it compares the calculated desired fuel rail pressure to the actual value to determine the FRP regulator position. When the actual fuel rail pressure is higher than the desired value, the FRP regulator is closed to decease the flow rate.

Conditions for Running the DTC

P0091

P0092

Conditions for Setting the DTC

P0091

The ECM detects that the FRP regulator solenoid drive current is less than 400 mA when the drive duty cycle is more than 70 percent.

P0092

The ECM detects that the FRP regulator solenoid drive current is more than 2700 mA when the drive duty cycle is less than 20 percent.

Action Taken When the DTC Sets

DTCs P0091 and P0092 are Type A DTCs.

Conditions for Clearing the DTC

DTCs P0091 and P0092 are Type A DTCs.

Diagnostic Aids

Inspect for any recent engine mechanical repairs. An incorrectly installed fuel rail pressure (FRP) sensor will cause this DTC to set.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Circuit/System Verification

Verify the integrity of the fuel system and fuel rail pressure sensor by inspecting for the following conditions:

Circuit/System Testing

Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the harness connector at the fuel rail pressure (FRP) regulator.
2. Ignition OFF, disconnect the harness connector at the control module.
3. Install a 3-amp fused jumper wire between the FRP regulator circuits.
4. Ignition ON, verify that a test lamp does not illuminate between the FRP regulator circuits and ground.

⇒	If the test lamp does illuminate, test the FRP regulator circuits for a short to battery voltage.

5. Connect the regulator, ignition OFF, test for between 1.9-2.3 ohms of resistance between FRP regulator circuits at the ECM connector.

⇒	If the resistance is more than 2 ohms or less than 1.8 ohms, test the FRP regulator for an open/high resistance. If the circuit tests normal, replace the ECM.

6. Ignition OFF, test for between 1.9-2.3 ohms of resistance between FRP regulator terminals.

⇒	If resistance is more than 2 ohms or less than 1.8 ohms at 20°C (68°F), test the FRP regulator for an open/high resistance. If the circuit tests normal, replace the FRP regulator.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.