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The car is a 2006 Mercury Mountaineer V6, got about 150k miles. The dealership sale rep is telling me my fuel rail pressure sensor is shorting out and needs to be replaced. Apparently, its causing too high of pressure and flooding out the engine. My symptoms are hesitation and bucking infrequently for a few weeks, and just recently engine cut out while I was driving down the road (this cut off was preceded by the bucking and hesitation experienced in the past).

The problem is the dealership is quoting me a total cost (parts & labor) of $650. The sales rep guy (not the mech) says most of this price is parts cost....which I do not believe. But I'm having trouble wrapping my mind around this.

  1. Is a fuel rail pressure sensor the same as a fuel injection pressure sensor? ..I understand the difference between rail sensor and a tank pressure sensor.
  2. I can get a fuel injection pressure sensor for around $90 (for my vehicle), so if this the same part, then I'm getting ripped...or no?

I edited to add this link: Difference between fuel pressure and fuel rail pressure

..which discusses the difference between a "fuel pressure" reading and "fuel rail pressure" reading. My understanding is that: one sensor is in the fuel tank and one in the rail where the injectors are located. My issue would, according to the dealership, be at the injector rail...which is why I was asking whether a "fuel injector pressure sensor" is the same as a "fuel rail pressure sensor" is the same function part.

For example, this part is a "Fuel Injection Pressure Sensor" on Amazon.com that should fit my 2006 Mountaineer: Standard Motor Products FPS5 Fuel Injection Pressure Sensor. If you read the amazon reviews, you will see several people saying this part fixed their "fuel rail pressure sensor" error and was a simple install...granted their vehicle is not likely the same as mine, but I am trying to figure out why this shop is quoting me a $650 cost to replace a $90 part. My general research does not indicate this as being a complex task in any vehicle.

I would like to know that I'm correct before I go chew someone's butt.


Ok well, after further research it appears that the $650 cost may be high but not unfairly ridiculous...if the sensor is under my intake manifold.

First, the part number is FPS5 and a fuel injector sensor is the same as a fuel rail sensor, at least for my purposes here. And all of my symptoms fully match with this type of sensor problem.

Second, the probable reason for the high cost is that, if my sensor is located underneath my intake manifold, it's a labor-intensive process. Plus, the dealership won't use aftermarket parts and the non-aftermarket part is around $190 rather than $90 for a new aftermarket part...I should just find a junk yard part. Lastly, removing the manifold will require new intake manifold gaskets, which just adds to the costs.

I don't have the car with me, but just checked a friend's 2007 V8 Explorer. The V8 has the sensor right on top of the rail, not covered by the intake manifold..it would only take two bolts to remove (after depressurizing the fuel rail and disconnecting battery, of course). But it looks like my 4.0L V6 engine (the mountaineer and explorer have same motor) will have the sensor under the intake manifold.

So my plan is to order the aftermarket part and get the dealership or someone else to replace it. But I will put eyes on my engine to make sure it is actually under the manifold before I pay anyone to replace the sensor. Plus, they should clean/degrease the manifold if I'm paying them to take off and put fresh gaskets on it.

If anyone has any input on all this, I'd love to hear it.

  • Welcome to Motor Vehicle Maintenance & Repair! I'm not seeing a fuel "injection" pressure sensor, but rather a "Fuel Pressure Sensor", but the price comes in at about what you're saying. Tell them you want a written itemized estimate. The written estimate will have a complete breakdown of what needs to be done for your vehicle. The part number of what you need will be on there, which you can use to cross reference and make sure you're looking at the right part. Then take your Mountaineer to another place and get a 2nd opinion. Dealership are invariably higher in price. – Pᴀᴜʟsᴛᴇʀ2 Oct 8 '17 at 21:02
  • Yea, I think you're absolutely right about getting a written estimate. Thanks. – LeeRoy Oct 8 '17 at 22:32

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