I’ve been chasing down these reading for a while now I’m getting stuck the car is very well serviced 85k miles 2006 Jaguar s type 3.0. clearly the voltage reading on the Fuel rail pressure sensor is absurdly high at
80 volts! almost a impossible reading that and the fuel rail pressure the reading don’t move at at all as if they are stuck even when driving so I’ve come to the forums to ask for help the wiring seems fine I will need to inspect it more I’ve already replaced the sensor I have no active lights on the dash but do see a code P0088 fuel rail pressure too high very confusing any help Willis be appreciate thank you guys!

 

Looks like a software bug in the tool.

OBD values are squeezed into very few bytes and have to be decoded. Looks like the decoding went wrong!

 

Before doing anything get a mechanical fuel pressure gauge on the car and actually measure what the fuel pressure is. As JagV8 posted there could be a problem with your scanner as that is not a Jaguar SDD system.

Here is what your fuel system looks like on the engine.
Note the red and green circles. Hopefully what you replaced was item #4? If so you should be able to find this test port easily.





Item #5 is the Schrader valve fuel pressure test point and on the V-6 is simple to access. This looks like a tire valve stem because it is. Now go to any auto parts house and use the free tool loaner program to borrow a mechanical fuel pressure gauge. Usually they will connect but on occasion I have had to use an adapter. I have always had V-8's so don't know if the V-6 uses a different Schrader valve or not. I "think" they are the same.

Let us know how that number compares to the scanner number. If it does read the same I would suspect the FPR you changed is bad.
Has the fuel pump and or filter been changed? Anytime I see issues like this the very first thing is to inspect and change the fuel filter.

Have you done this?
What did it look like?
One last thing? The FPR is manifold pressure referenced. Have you measured the vacuum signal at the FPR? It does not show it in my pictures but the FPR should have a vacuum hose attached and an electrical plug.
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Wasn't that feature omitted on the late model V6? On my '02 V6, the test port is right out in the open, just forward of the oil filler cap. But on the later V6, I'm thinking you had to rig up a special adapter to connect a mechanical test gauge.

 

The vacuum hose that connects from the FPR to the back of the intake is in tact. I have also replaced the FPR with a OEM one from the junkyard last week got a new one this week tested resistance on both sensor with them out the car and they seem within spec. Highly doubtful that the scanner is giving me a bad reading I’ve used multiple high end scanners and have gotten the same data. I have changed the fuel filter, I have not changed any fuel pumps.the car starts and runs fine at first but let’s say I randomly step really heavy on the gas it will intermittently blink and misfire only sometimes, then shortly after clear itself up and it doesn’t always do that. Fuel pressure is also within spec weird enough. I most likely am going to have someone inspect all the wiring for me.

 

This is very strange. This is the value reported by your scanner? Does your car have the port to connect a mechanical test gauge? (See my previous message, thinking your car won't have it).

If there is a test port, make sure the actual fuel pressure agrees with the scanner value. The PCM uses the sensor input to control the output from the pump. If the sensor input was inaccurate, the computer will unknowingly but happily adjust pump output to the erroneous value.


Wiring diagrams are here, near the top of the page:

JagRepair.com - Jaguar Repair Information Resource


Open the diagram for 2005 and scroll to figure 03.1 for the V6. The suspect sensor is called the "IP Sensor" and is illustrated near the top right of the page.

First thing I'd try is unplugging the connector from the sensor. If the voltage reading still remains high, the wiring is most likely at fault. (A PCM fault is very rare.) You can further break down the wiring run by disconnecting plug 1L10. This is a black 12 pin connector, near the rear of the engine. No further location details are given, but you should be able to follow the harness back from the sensor. If the high reading only clears by disconnecting 1L10, the fault is between that connector and the sensor.

 

I appreciate the fast and knowledgeable response. That sounds like a great idea I will put the sensor back into the rail plug it in turn the car on while looking at the live data and then unplug the sensor while the car is running and see if the voltage stays at 80 or if it drops and going back to the test port sadly my car does not have that test port.

 

A couple more thoughts.

You won't need the engine running to do as you are thinking. Key to the On position without starting the engine should be sufficient.

Without the test port, verifying the sensor accuracy will be a little trickier. Try removing pressure from the fuel rail and see what the scanner reports. One idea is to pull the fuse for the fuel pump. Start the engine and it will quickly die as the remaining fuel is consumed, dropping injector rail pressure to zero or nearly so. Key on, see what your scanner shows now. This doesn't check the accuracy in the normal running range (40 PSI?) but will give you at least one data point.

 

ok so I unplugged the FRP sensor at the rail and turned the battery on my car didn’t start it like you said just the battery and as soon as I got the live data up and running it was reading 80.74 volts and the KPA was 265 again stuck with the sensor unplugged does that indicate a major short in the wiring maybe?

 

If still showing 265 KPA with the sensor unplugged, that would point towards a wiring fault. Maybe there's a bare spot in a wire rubbing to ground or against another wire? Try shaking down the harness while watching the scanner. See if the numbers change.

 

The V-6 and V-8 both had test ports at one time. Yes over the years Jaguar started deleting content. On the V-8's I know the 2006+ do not have the test port. The V-6's I am not sure of the years. Too bad your does not.

Yes unplugging the vacuum hose from the FPR will default the fuel pressure to around 70 psi and the car should run. Without a test port I am not sure how to determine if the FPR is good or not?
Post back with what you get with the fuel pump unhooked.
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Monday after work I’m going to pull the Manifold off with one of my friends and and we will test resistance on the fuel rail sub harness and other tests with probes and other sorts or things, my friend is good with electrical and he’s gonna test that for me he been browsing the electrical diagrams and has a good idea now and was saying the same thing about maybe a wire rubbing against a ground or something small like that thankfully if it’s just the subharness that should be a easy repair,I will get back to you when I have things sorted out I appreciate the help.🙏

 

I’ve replaced the sensor twice one OEM original one from the junkyard and brand new one both gave me the exact same reading even when i unplugged connector from the FRP sensor the readings stayed the same, no fluctuations seems like it may have a short going to test the whole fuel rail sub-harness for shorts and report back with what I find.

 

For giggles, try disconnecting the plug on the fuel temperature sensor. It's located near the front of the injector fuel rail.

Looking at the wiring diagram, it's on the same branch circuit as the fuel pressure sensor. Kind of a long shot, but maybe a problem with that sensor is affecting the reading from the pressure sensor. Would only take a few minutes to try.

 

sounds good I appreciate the extra info I will make sure to try that as well!