Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0191: Fuel Rail Pressure (FRP) Sensor PerformanceDiagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage |
|---|---|---|---|---|
FRP Signal | P0192 | P0088, P0191 | P0193 | P009E, P0193 |
FRP Low Reference | -- | P0191 | P0193 | ¹ |
FRP 5-Volt Reference | P0117, P0462, P0522, P0652 | P0087, P0191 | P0193 | P0118, P0463, P0653, P2454 |
Fuel Pressure Regulator Solenoid Supply Voltage | P0088, P0090 | P0088 | P0090 | P0087, P0191, P2510 |
¹ 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
| • | DTCs P0016, P062F, P0116, P0117, P0118, P0192, P0193, P0652 or P0653 are not set. |
| • | The ignition is ON, after the engine has been OFF for greater than 20 minutes. |
| • | The coolant temperature is warmer than 40°C (104°F). |
| OR |
| • | The ignition has been OFF greater than 60 seconds. |
| • | The fuel temperature is more than 60°C (140°F). |
| • | This diagnostic runs continuously within the above conditions. |
Conditions for Setting the DTC
The FRP sensor is below 0.352 volt or above 0.650 volt within the Conditions for Running the DTC.
Action Taken When the DTC Sets
DTC P0191 is a Type A DTC.
Conditions for Clearing the MIL/DTC
DTC P0191 is a Type A DTC.
Reference Information
Schematic Reference
Connector End View Reference
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
Note:
• You must perform the Circuit/System Verification before proceeding with Circuit/System Testing. • 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. • Disregard Freeze Frame/Failure Records if the engine RPM parameter displays greater than zero.
- If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.
- Observe the Fuel Rail Pressure Sensor 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.
- Engine running, observe the DTC information with a scan tool. DTC P0191 should not set.
- 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
Note: Fuel pressure control will be disable if DTC P0087, P0088, P0192, or P0193 are set. Codes must be cleared to enable the device control.
- Turn OFF the ignition.
- Disconnect the ECM connector and the fuel pressure regulator connector.
- Test the fuel pressure regulator solenoid supply voltage circuit for a short to voltage.
- Disconnect the FRP sensor.
- 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
