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Technical Ducato Fuel Pressure Sensor

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Technical Ducato Fuel Pressure Sensor

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DSDRBozzy

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Feb 14, 2020
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Location
Brisbane Australia
Hi all,

Firstly, apologies for the long post, i didn't intend it to be quite so big, but some extra info might help you to help me :wave:

I have a 2014 Fiat Ducato 3.0lt 180 multijet with an F1CE3481E engine.

Have been having an ongoing issue with a P0091 fault code.

It originally happened if I was travelling at highway speeds (90 to 100kph) and needed to put the foot down to overtake another vehicle.

Check engine light would come on, loss of torque and all live fuel info on the dash would zero out (distance to empty, current fuel economy etc) turning van off and back on would resume normal function.

My diagnostic reader at that time would repeatedly spit out P0091 and P0190 codes.

I'm not getting any black smoke at all and the van was used by a previous owner as a courier van up until June 2019 with what I have worked out a pretty even split of highway and city driving.

Had it at a euro specialist who firstly replaced the Fuel Pressure Regulator on the high pressure fuel pump which made no difference, then the low pressure pump in the fuel tank was replaced and also made no difference except that I'm no longer getting the P0190 code.

That put a big dent in the bank account, so I haven't had it back at the mechanic since, but the P0091 persists and now occurs more frequently and at lower speeds.

I have checked the fuel pressure sensor on the fuel rail and come up with the following, can anyone here advise if these voltages are within spec? as I have found the diagram below but don't completely understand it. :confused:

Earth and 5v power were the same across all testing, below are the signal voltages.

Key On - engine NOT running - sensor unplugged
5v Signal

Key On - engine NOT running - sensor plugged in
0.52v Signal

Key On - Engine Running @ Idle
1.4v Signal

Key On - Engine Running @ 2000 and 3000rpm
Signal did not exceed 2v


I'm also open to suggestions for things to look at, I'm thinking the next area to look at is the wiring loom in more detail, what I have been able to see so far looks ok with no broken or worn wires, but I didn't dive into it as deeply as it probably required.


Many thanks for any advice that may help me regain my sanity and prevent this thing from being lit on fire. :bang:

Cheers Michael
 
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Hi DSDRbozzy

I believe that :

P0091 means that the control signal from the pressure sensor is too low
P0190 means that the control signal is not the expected value for the engine operating conditions.
Bear in mind though that Fiat may have subtly different definitions for these codes.


From the figures you give plus the sensor graph, it looks like the Rail Pressure at idle is about 25 MPa (250 Bar) and when revving about 63 MPa (630 Bar). You don't say if the revving figure is under load or just stationary and revving in neutral. If it's in neutral the fuel demand will not be very great so the fairly low pressure might be expected. When running under load, something nearer 100 to 200 MPa (1000 to 2000 Bar) would be correct, though I don't have the exact figures for the Ducato.

It seems to me that during your test the sensor was giving the correct reading, but on the road something is causing the rail fuel pressure to be lower than it should when the fuel demand rises above a certain amount (foot down). As you will appreciate, there are quite a few components between the tank and the rail, any one of which could be responsible and some of which have been attended to already. I think you should turn your attention to anything else that could be restricting fuel flow, which in turn will cause lower than normal pressure at the input of the HP pump.


The puzzle to me is that I would expect restricted flow to throw a P0190 code. The P0091 would be more symptomatic of a wiring fault (short circuit) pulling down the control signal from the sensor to below its minimum value of 1 volt. However, intermittent short circuits tend to happen at random, not just when overtaking !
 
Thanks for the reply Anthony,

Revving is while in neutral, not sure I'd have much success driving around with the multimeter connected to the sensor, assuming I did, would normal operation expect to see the signal voltage increase upwards of 2.6v under load?

I feel like it's going to end up being a high pressure fuel pump.

Might go talk to a mechanic near work who I've noticed works on Fiat based motorhomes as half the battle is not having the equipment and knowledge to be messing around too much with fuel systems, the other half is the expense (n)
 
Ive been compiling a list of codes from various sources including here

Fiat 2 P0091 Drift positive rail pressure (step 1) - low pressure, Positive drift
Ducato P0091 Fuel Pressure (Regulator at High Pressure Pump Inlet)
Generic P0091 Fuel Pressure Regulator 1 Control Circuit Low
Fiat 2 P0190 Fault electric rail pressure sensor,
Ducato P0190 Fuel High Pressure Sensor
Generic P0190 Fuel Rail Pressure Sensor Circuit Malfunction

To those that know they may be subtly different. (I haven't a clue)
Are you sorted or still spending?
 
Nah the problem remains, not in a position to throw cash at it, hoping to see mechanic next week and see what they can make of it all.

Did manage to dig a bit deeper into the main wiring looms and found a wire that a previous owner has run) comes from the ecu behind the engine bay fuse box and runs over and down behind the engine on the left side (standing in front of van looking into engine bay)
 
Last edited:
DSDRBozzy said:
Revving is while in neutral, not sure I'd have much success driving around with the multimeter connected to the sensor, assuming I did, would normal operation expect to see the signal voltage increase upwards of 2.6v under load?
Click to expand...

Just on this point, if you use diagnostic software such as MultiEcuScan, you can drive or operate the engine with the laptop plugged in to the OBD port and record desired parameters including actual fuel pressure vs. required fuel pressure, pressure sensor voltage etc. and compare to the signal vs. pressure as indicated in DSDRBozzy's diagram.

That diagram is from the Fiat workshop manual "eLearn" which you can get from the downloads section of this site, and which contains a great deal of useful information.
 
Yeah I think I'll spring for multiecuscan.

I currently have the Torque app with my elm327 reader.

I went for a drive today and forced the error to occur few times.

This is the only information I was able to get (hope there's 4 different screenshots below..it's a pain posting from the phone.


Not sure how to interpret the info, but it's something to take to the mechanic I guess.

photo_popup.php



photo_popup.php

photo_popup.php
 
Freeze frame information:
------------------
Engine Load = 91.765 %
Engine Coolant Temperature = 60 °C
Intake Manifold Pressure = 202 kpa
Engine RPM = 1,846.5 rpm
Speed (OBD) = 77 km/h
Intake Air Temperature = 48 °C
Mass Air Flow Rate = 111.44 g/s
Fuel Rail Pressure = 105,980 kpa


Freeze frame information:
------------------
Engine Load = 91.765 %
Engine Coolant Temperature = 60 °C
Intake Manifold Pressure = 202 kpa
Engine RPM = 1,846.5 rpm
Speed (OBD) = 77 km/h
Intake Air Temperature = 48 °C
Mass Air Flow Rate = 111.44 g/s
Fuel Rail Pressure = 117,470 kpa


Freeze frame information:
------------------
Engine Load = 91.765 %
Engine Coolant Temperature = 60 °C
Intake Manifold Pressure = 202 kpa
Engine RPM = 1,846.5 rpm
Speed (OBD) = 77 km/h
Intake Air Temperature = 48 °C
Mass Air Flow Rate = 111.44 g/s
Fuel Rail Pressure = 101,830 kpa


Freeze frame information:
------------------
Engine Load = 91.765 %
Engine Coolant Temperature = 60 °C
Intake Manifold Pressure = 202 kpa
Engine RPM = 1,846.5 rpm
Speed (OBD) = 77 km/h
Intake Air Temperature = 48 °C
Mass Air Flow Rate = 111.44 g/s
Fuel Rail Pressure = 101,830 kpa
 
Last edited:
Hi DSDRBozzy,

I am not able to offer further advice, but I would like to contribute the following observations on your test results.

The only difference between all 4 results is fuel pressure, and results 3 and 4 seem to be identical?

Engine temperature is rather low at 60 C.

I would have expected some variation in engine output, and rpm over the 4 sets of readings.


I had to smile at your use of the expressive ancient Anglo Saxon "Nah" in your previous post.
 
Michael

Did the euro specialist garage you mention carry out any fault finding or just replace the high pressure regulator as that is the part mentioned in the fault code?

Have you renewed the fuel filter?

Similar issues on my 2.3 x250 this time last year. Fault code P0091 present. Would run OK until under hard acceleration at which point it would cut out. Live data on multiECU scan was useful plotting desired fuel pressure vs actual fuel pressure. This showed when driving under load the actual fuel pressure did not maintain pace with desired fuel pressure before finally cutting out.

Pulled the fuel filter out to find it completely choked. Very dirty and covered in gel/waxy diesel. Fuel filter changed only 22000 miles ago so I think it was a combination of contaminated fuel at some point in the past and summer diesel still in the fuel tank starting to wax up and blocking the filter.

New filter and good as new.

Cheers

Sean
 
Last edited:
scsmyth said:
Michael

Did the euro specialist garage you mention carry out any fault finding or just replace the high pressure regulator as that is the part mentioned in the fault code?

Have you renewed the fuel filter?

Similar issues on my 2.3 x250 this time last year. Fault code P0091 present. Would run OK until under hard acceleration at which point it would cut out. Live data on multiECU scan was useful plotting desired fuel pressure vs actual fuel pressure. This showed when driving under load the actual fuel pressure did not maintain pace with desired fuel pressure before finally cutting out.

Pulled the fuel filter out to find it completely choked. Very dirty and covered in gel/waxy diesel. Fuel filter changed only 22000 miles ago so I think it was a combination of contaminated fuel at some point in the past and summer diesel still in the fuel tank starting to wax up and blocking the filter.

New filter and good as new.

Cheers

Sean
Click to expand...

Regarding the diagnostic part I think they just replaced the parts with minimal fault finding.


Fuel filter was replaced before or after the regulator i can't remember when. But it was replaced.(they didn't actually charge for it)


My obd scanner and app do actual pre but not desired but I can see a massive drop off at the time the check engine light comes on. I'll post pic of the spreadsheet.
 
DSDRBozzy said:
Hi all,

Firstly, apologies for the long post, i didn't intend it to be quite so big, but some extra info might help you to help me 👋

I have a 2014 Fiat Ducato 3.0lt 180 multijet with an F1CE3481E engine.

Have been having an ongoing issue with a P0091 fault code.

It originally happened if I was travelling at highway speeds (90 to 100kph) and needed to put the foot down to overtake another vehicle.

Check engine light would come on, loss of torque and all live fuel info on the dash would zero out (distance to empty, current fuel economy etc) turning van off and back on would resume normal function.

My diagnostic reader at that time would repeatedly spit out P0091 and P0190 codes.

I'm not getting any black smoke at all and the van was used by a previous owner as a courier van up until June 2019 with what I have worked out a pretty even split of highway and city driving.

Had it at a euro specialist who firstly replaced the Fuel Pressure Regulator on the high pressure fuel pump which made no difference, then the low pressure pump in the fuel tank was replaced and also made no difference except that I'm no longer getting the P0190 code.

That put a big dent in the bank account, so I haven't had it back at the mechanic since, but the P0091 persists and now occurs more frequently and at lower speeds.

I have checked the fuel pressure sensor on the fuel rail and come up with the following, can anyone here advise if these voltages are within spec? as I have found the diagram below but don't completely understand it. :confundido:

La potencia de tierra y 5v fue la misma en todas las pruebas, a continuación se muestran los voltajes de la señal.

Llave encendida - motor NO funcionando - sensor desenchufado
señal de 5v

Llave encendida - motor NO funcionando - sensor enchufado
señal de 0.52v

Llave encendida - Motor funcionando en ralentí
señal de 1,4 v

Llave encendida - Motor funcionando a 2000 y 3000 rpm
La señal no superó los 2v


También estoy abierto a sugerencias de cosas para mirar, estoy pensando que la siguiente área para mirar es el telar de cableado con más detalle, lo que he podido ver hasta ahora se ve bien sin cables rotos o desgastados, pero No me sumergí tan profundamente como probablemente requería.


Muchas gracias por cualquier consejo que pueda ayudarme a recuperar la cordura y evitar que esto se incendie. :estallido:

saludos miguel
Click to expand...
Hola amigo .que pasó al final con tu furgoneta?Lo arreglaste.Tengo el mismo problema con la misma furgoneta.No encuentro el fallo.He cambiado todos los senzores y nada.
 
DSDRBozzy said:
Hi all,

Firstly, apologies for the long post, i didn't intend it to be quite so big, but some extra info might help you to help me 👋

I have a 2014 Fiat Ducato 3.0lt 180 multijet with an F1CE3481E engine.

Have been having an ongoing issue with a P0091 fault code.

It originally happened if I was travelling at highway speeds (90 to 100kph) and needed to put the foot down to overtake another vehicle.

Check engine light would come on, loss of torque and all live fuel info on the dash would zero out (distance to empty, current fuel economy etc) turning van off and back on would resume normal function.

My diagnostic reader at that time would repeatedly spit out P0091 and P0190 codes.

I'm not getting any black smoke at all and the van was used by a previous owner as a courier van up until June 2019 with what I have worked out a pretty even split of highway and city driving.

Had it at a euro specialist who firstly replaced the Fuel Pressure Regulator on the high pressure fuel pump which made no difference, then the low pressure pump in the fuel tank was replaced and also made no difference except that I'm no longer getting the P0190 code.

That put a big dent in the bank account, so I haven't had it back at the mechanic since, but the P0091 persists and now occurs more frequently and at lower speeds.

I have checked the fuel pressure sensor on the fuel rail and come up with the following, can anyone here advise if these voltages are within spec? as I have found the diagram below but don't completely understand it. :confused:

Earth and 5v power were the same across all testing, below are the signal voltages.

Key On - engine NOT running - sensor unplugged
5v Signal

Key On - engine NOT running - sensor plugged in
0.52v Signal

Key On - Engine Running @ Idle
1.4v Signal

Key On - Engine Running @ 2000 and 3000rpm
Signal did not exceed 2v


I'm also open to suggestions for things to look at, I'm thinking the next area to look at is the wiring loom in more detail, what I have been able to see so far looks ok with no broken or worn wires, but I didn't dive into it as deeply as it probably required.


Many thanks for any advice that may help me regain my sanity and prevent this thing from being lit on fire. :bang:

Cheers Michael
Click to expand...
Hi Michael, Did you get a resolution to this issue? I have a 2014 180 Mutijet doing exactly the same thing. FIAT said it was a faulty Turbo sensor that was built into the sensor, so replaced the turbo but still have the same issue! Luckily the turbo was buggered too, so didn't waste $5k~
 
ddkdave said:
Hi Michael, Did you get a resolution to this issue? I have a 2014 180 Mutijet doing exactly the same thing. FIAT said it was a faulty Turbo sensor that was built into the sensor, so replaced the turbo but still have the same issue! Luckily the turbo was buggered too, so didn't waste $5k~
Click to expand...
Sorry Dave, haven't been on here for a while. Hopefully you have already had yours sorted, but just incase.

Eventually got it into MTQ Engine Systems in Brisbane, initially thought it was the fuel rail pressure sensor and changed the rail (sensor not replaceable on its own) ended up being the high pressure fuel pump.

Was relieved to finally get it sorted.
 
DSDRBozzy said:
Eventually got it into MTQ Engine Systems in Brisbane, initially thought it was the fuel rail pressure sensor and changed the rail (sensor not replaceable on its own) ended up being the high pressure fuel pump.
Click to expand...
That's "interesting". I would have expected to change the sensor only. It does not make sense to remove 5 extremely high pressure connections to the pump and injectore instead. Further there was a recommendation that fuel pipes are not re-used.
 
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