Engine-Codes - Ford - P0191 FORD

P0191 FORD - Fuel Rail Pressure Sensor Circuit Range/Performance

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What is this?
Table of contents

P0191 FORD Possible Causes

  • 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 is the P0191 FORD code repair?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

Tech Notes













User Submitted Video

What is the cost to diagnose the P0191 FORD code

Labor: 1.0

The cost to diagnose the P0191 FORD code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.
How much do you know about cars?

Take the AutoCodes.com automotive tests and turbo-charge your car repair knowledge

Play Now

Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Engine will not start

P0191 FORD Meaning

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.

More Information

Need more information on how to fix the P0191 FORD code?
Get Access to Factory Service Manuals

Need more help?

Get the P0191 Ford code diagnosed by a professional: Find a repair shop in your area