Ford Fusion P0191:  Fuel Rail Pressure Sensor → Circuit “A” → Range/Performance


P0191 Ford Fusion

P0191 is a common OBD-II code.  It indicates that the fuel rail pressure sensor is receiving a signal that is outside of its normal range.  This is a generic code, which indicates that it has the same meaning for the Ford Fusion as it would any other vehicle.  


P0191 is typically caused by a bad fuel pressure sensor, fuel pressure regulator, or an issue with the fuel rail pressure sensor wiring harness.


P0191 Symptoms:  Ford Fusion

Ford Fusion P0191 Diagnosis


When P0191 is present, there typically are noticeable symptoms.  Drivability is usually affected.

Here are the most common symptoms of P0191:



If there isn’t enough fuel pressure getting to the fuel injectors, the engine may stall out or hesitate in certain situations.


Air/Fuel Mixture Issues

Without a reliable reading from the fuel pressure sensor, your Fusion may end up with the wrong air/fuel mixture.  If it runs too rich, you may get black smoke and P0172.  If it runs too lean, you’re likely to have p0171 accompany P0191.


Unreliable Idle

P0191 can be caused when the fuel pressure regulator is bad.  If the fuel pressure at the injectors is inconsistent, it’ll be really hard for your Fusion to maintain a steady idle speed.  This can lead to the engine dying when coming to a stop as well.


Poor Fuel Mileage

Fuel mileage can suffer when the air/fuel mixture isn’t correct.


P0191 Causes:  Ford Fusion

Here are the most common issues that cause P0191 to be thrown:


Fuel Pressure Sensor

The fuel pressure sensor is responsible for telling your Fusion’s ECM/PCM what the actual fuel pressure of the vehicle is.  If it goes bad (or if the fuel pressure really is out of the normal range) P0191 can and will appear.

A bad fuel pressure sensor can force the vehicle to overwork the fuel pump, thinking that it’s constantly starving for fuel when it is not.



Wiring issues can cause P0191 to be thrown.  Take a look at the wiring harness around the fuel pressure sensor.  Does it look broken or damaged?  Is the connection to the sensor solid?  If it looks bad, it may need to be replaced.


Fuel Pressure Regulator

The fuel pressure regulator is responsible for making sure that the amount of fuel pressure that reaches the fuel rail is at a constant level (which will be less than pushed by the fuel pump).  If it goes bad, it can restrict the flow of fuel to the point that P0191 can be thrown.

Ford Fusion: Bad Fuel Pressure Regulator Diagnosis


Fuel Pump

A bad fuel pump would act exactly like a bad fuel pressure regulator.  You’d notice hesitation and stalling as the fuel pump struggles to keep up with the demands of the engine.  This is typically noticed under heavy engine load.  Or, right after heavy engine load when the fuel pressure isn’t recovered enough for a proper idle.

See Also:  Ford Fusion: Bad Fuel Pump


P0191 Diagnosis:  Ford Fusion

Here’s a great video from Airtex:


A good scanner can help you look at the conditions that were present when the code was set.  You can also use it to check the fuel pressure reading as you drive.  If the reading seems off, you’ll need to manually check the fuel pressure.  

If the manual fuel pressure reading is normal, then you know that you’ve got an issue with the fuel pressure sensor (or the wiring going to and from it).  If the fuel pressure reading is low, than you’re going to need to figure out if it’s the fuel pump or fuel pressure regulator that is causing P0191.



P0191 can be a difficult code to track down, but should not be ignored.  Doing so very well could leave your Ford Fusion stranded.  If there is anything that you would like to add, please leave a comment below.  Good luck.