AutoCodes – Ford – P0191 2008 Ford Fusion

P0191 2008 Ford Fusion Code - Fuel Rail Pressure Sensor Circuit Range/Performance

Quick Answer

The Fuel Rail Pressure (FRP) Sensor is a diaphragm strain gauge device. Common causes include Low or no fuel, Faulty Fuel Rail Pressure (FRP) Sensor, FRP harness is open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0191 2008 Ford Fusion indicates Fuel Rail Pressure Sensor Circuit Range/Performance.
Common causes: Common causes include Low or no fuel, Faulty Fuel Rail Pressure (FRP) Sensor, FRP harness is open or shorted.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 4,568

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 26, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0191 2008 Ford Fusion Description

The Fuel Rail Pressure (FRP) Sensor is a diaphragm strain gauge device. The FRP sensor measures the pressure difference between the fuel rail and atmospheric pressure. The FRP sensor nominal output varies between 0.5 and 4.5 volts, with 0.5 volts corresponding to 0 MPa (0 psi) gauge and 4.5 volts corresponding to 26 MPa (3771 psi) gauge. The sensor can read vacuums and may lower the output voltage to slightly below 0.5 volts. This condition is normal and is usually the case after several hours of cold soak before the vehicle dome light is turned on. The FP module is energized at the same time the dome light is commanded on. A disabled or malfunctioning dome light does not affect the FP module control.
The FRP sensor is located on the fuel rail and provides a feedback signal to indicate the fuel rail pressure to the Powertrain Control Module (PCM). The PCM uses the FRP signal to command the correct injector timing and pulse width for correct fuel delivery at all speed and load conditions. The FRP sensor, along with the fuel volume regulator (part of the fuel injection pump), forms a closed loop fuel pressure control system. An electrically faulted FRP sensor results in the deactivation of the fuel injection pump. Fuel pressure to injectors is then provided only by the FP module. When the fuel injection pump is de-energized and the injectors are active, the fuel rail pressure is approximately 70 kPa (10 psi) lower than FP module pressure due to the pressure drop across the fuel injection pump. Thus, if the FP module pressure is 448 kPa (65 psi), then the fuel rail pressure would be approximately 379 kPa (55 psi) if the injectors are active.

OBDII Code P0191 2008 Ford Fusion - Fuel Rail Pressure Sensor Circuit Range/Performance - AutoCodes.com — P0191 2008 Ford Fusion Code - Fuel Rail Pressure Sensor Circuit Range/Performance

What does this mean?

What are the Possible Causes of the DTC P0191 2008 Ford Fusion?

Low or no fuel
Faulty Fuel Rail Pressure (FRP) Sensor
FRP harness is open or shorted
FRP circuit poor electrical connection
Faulty Fuel Pump

How to Fix the DTC P0191 2008 Ford Fusion?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0191 2008 Ford Fusion code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0191 2008 Ford Fusion Code

1. What does OBDII code P0191 mean on a 2008 Ford Fusion?

Code P0191 indicates a problem with the Fuel Rail Pressure Sensor Circuit, specifically that the sensor is reporting a pressure value outside of the expected range or performance parameters.

2. What are the common symptoms of P0191 in a 2008 Ford Fusion?

Symptoms may include difficulty starting, engine stalling, reduced power, rough idling, poor acceleration, or the Check Engine Light being illuminated.

3. What causes the P0191 code to appear on a 2008 Ford Fusion?

Common causes include a faulty fuel rail pressure sensor, wiring or connector issues in the sensor circuit, fuel pump problems, a clogged fuel filter, or low fuel pressure.

4. Can I drive my 2008 Ford Fusion with the P0191 code?

Driving with this code is not recommended as it may lead to poor performance, stalling, or even engine damage due to improper fuel delivery.

5. How do I diagnose the P0191 code on a 2008 Ford Fusion?

Start by checking the fuel rail pressure sensor and its wiring for damage or poor connections. Verify fuel pressure with a gauge and inspect the fuel pump and fuel filter for issues.

6. What repairs are typically needed to fix P0191 on a 2008 Ford Fusion?

Repairs may include replacing the fuel rail pressure sensor, repairing or replacing damaged wiring, cleaning or replacing the fuel filter, or addressing issues with the fuel pump.

7. How much does it cost to fix the P0191 code on a 2008 Ford Fusion?

The cost depends on the issue. Replacing a fuel rail pressure sensor may cost $100-$300, while fuel pump replacement can exceed $500, including labor.

8. Can a dirty fuel filter cause the P0191 code on a 2008 Ford Fusion?

Yes, a clogged fuel filter can restrict fuel flow, causing low pressure and triggering the P0191 code.

9. What tools are needed to troubleshoot the P0191 code on a 2008 Ford Fusion?

You'll need an OBDII scanner, a fuel pressure gauge, and basic tools for inspecting and repairing wiring or components.

10. Does a failing fuel rail pressure sensor always trigger the P0191 code?

Not always. While a failing sensor is a common cause, wiring issues, fuel delivery problems, or other components in the fuel system can also trigger the code.