Merry Christmas, Fellow Jag enthusiasts. While finishing shopping last night, I accelerated from a stop light and at probable 3,000 to 4,000 rpm, the car lost power, went into restricted performance, and threw a CEL.and limped home. When parked, I shut it off and it started again very hard, and won't keep running. I checked the codes, and it is showing a P0193, "Fuel Rail Pressure Sensor Circuit High Input". Doesn't seem to be a lot of information about this. From what I gather:

1)-"Sensor High Input" is not the pressure, but the voltage at the sensor?

2)-Though I cannot find information in this or other Jag boards, I found information on the same sensor on a Land Rover 5.0 supercharged. It stated that if this sensor is shorted internally, it will read 5v, and that a reading of 5v is an internally shorted sensor. Can anyone corroborate that this is the case on the Jag 5.0 s/c version as well?

3)-Under these circumstances, are there any more likely scenarios that would cause the P0193 and 5v conditions?

4)-I can see that the sensor is at the rear of the right rail. How terrible is it to get to?

Thanks, for your valued input!

John

 

Before starting out on any diagnosis, check available system voltage. Use a voltmeter to read the voltage across the battery terminals with the ignition in the OFF position. There should be a minimum of 12.6 volts.

You can also check the fuel pressure to the fuel rails using the Torque app and smart phone by connecting to the PCM through the OBD port via a Bluetooth interface. At idle, the AJ133/126 should have around 150 bar of fuel pressure.

 

Thanks for the input. Since I felt the battery was aging, as it was maybe 4 or 5 years old. It was at 12.5 switched off, and dropped to 12.0 when switched on. Lately, I have seen several low battery warnings. I installed a new AGM battery today, since it seemed about time. No start/won't keep running condition unchanged, as is the 5v sensor output.

 

What is the fuel pressure to the injectors?

 

I have a scanner with JLR software. I read the PCM with ignition on/engine off, and while poorly (and momentarily) running, They were both the same, at:

Fuel rail pressure sensor - High range sensor - 5v
Fuel rail pressure - Desired - 1450 psi
Fuel rail pressure - 2886 psi
Fuel rail pressure high range sensor - 98.5 psi

When starting/running poorly all stayed the same except:
Fuel rail pressure high range sensor - 94.6 psi

How can the FRP be that high with a non running engine? Not sure if any of these correlate to the pressure to the injectors, but surmise that it is the "Fuel rail pressure".

I appreciate your suggestions.

John

 

Enosgl, replacing that sensor is not too bad. You will need to remove the support that runs from the engine to the fire wall (this will require removing the cowl to get to two T55 torx bolts). From there, you should be able to reach back down in that area and access the sensor. I just replaced mine this summer. You will need to remove the insulation on top of the valve cover there too. Make sure to disconnect the two vacuum lines there to make removing the insulation a lot easier.

 

Thanks, Thermo. Just curious, what symptoms were you having when you failed. Similar to what I described?

Thanks again.

 

Enossgl, well, mine I think was actually a clogged fuel injector caused by bad maintenance by a shop. I had a water pump (and associated piping) fail while I was on vacation. So, I let a non-jag shop replace the water pump (figured it was an easy enough job for a shop like they were to do). Well, after a week of them having the car, I get a call that they have replaced the water pump, but now the car will not run. I got the car to start, but it was running very rich and I had to keep my foot in the gas to keep the engine even at idle. Needless to say, the CEL was flashing. I had the same high fuel rail pressure code. So, I ended up replacing the sensor first as that was the easiest and cheapest thing. That didn't fix it. So, I next replaced the 2 high pressure fuel pumps. Knowing that at this point, I was most likely looking at replacing fuel injectors I bit the bullet and took it to a local indy shop and after 8 fuel injectors, the car was running like it should again. Of note, as I was making these repairs, the car was slowly coming around, but still was having serious issues with running satisfactorily. What I suspect happened was when they replaced the water pump, they pulled the fuel line that runs across the top of the motor and got something into the fuel rail. This clogged #4 or #6 injector, causing the one cylinder to run extremely rich.

 

Thanks for the info, Thermo. With all of that going on, did you not throw any other error codes, ie, misfires, rich cylinder, etc? Puzzling to me is the 5v, which I have read is what they default to when they internally short, and a FRP of 2,800 psi.

Thanks again!

 

Oh, i was throwing all sorts of P030X codes, the wrong fuel pressure, P141X codes for cat efficiency, etc.

 

Thanks, Thermo. That may be good news. The ONLY code I am throwing is a P0193.

 

Happily, the sensor did the trick. Found a Bosch replacement on line and delivered it was $100.00. Labor at an indy in Lake Forest, IL I am friends with charged 1 1/2 hours to put it in, and as suspected, it fired right up and runs perfectly.

Thanks for the advice and suggestions!