Low Fuel Rail Pressure

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
So, the Golf went into limp mode with the flashing GP light about a month ago. Turned it off then back on and it was fine again, so I didn't worry about it. Drove it down to Baltimore without any problems then, a couple of days after fueling up, it happened again, this time also with a MIL. Hooked up VCDS and found two fault codes, 5211 and 39742. Looking at the Ross-Tech Wiki, among the possible causes was clogged fuel filter. I changed the filter and the old one looked very dirty with only ~17 K miles on it, so I assumed that I got a bad load of fuel. There was neither water nor metal shavings in the filter canister. After changing the filter all was back to normal and I could put the pedal down without issues. After a week or so, it happened again while I was accelerating through a turn, so I put in a new filter, but this time it went into limp mode the first time I tried to accelerate hard. The car drives fine even easily getting up to highway speed as long as I am gentle on the pedal, but goes into limp mode if I try to push it. The car has ~56K miles on the clock. Thoughts?
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Pull the control solenoid off the top of the HPFP and look at its little screen, see if there is any debris in there.
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
Thanks, Brian! We're in RI now but heading back down for Thanksgiving so I'll have a look then. I drove a U-Haul up this time and left the car in the garage in Baltimore...
 

borninabus

Veteran Member
Joined
Feb 18, 2020
Location
Arizona
TDI
-2013 JSW 6MT- -2006 Jetta DSG-
i was having some issues like this on my JSW.
very intermittent. same codes.
dug into it. HPFP, fuel filter and sensor screen were super clean.

i replaced the fuel filter and primed the system properly with VCDS and all is well now.
good luck (y)
 
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thundershorts

Top Post Dawg
Joined
Jul 15, 2010
Location
west chester pa
TDI
2015 passat tdi sel premium 2015 golf s tdi gls tdi b5.5, 2002 eurovan,Peugeot 505 td,Citroen cx25 prestige
sounds like your lift pump is on its way out.
 

thundershorts

Top Post Dawg
Joined
Jul 15, 2010
Location
west chester pa
TDI
2015 passat tdi sel premium 2015 golf s tdi gls tdi b5.5, 2002 eurovan,Peugeot 505 td,Citroen cx25 prestige
the good news art is the upgraded replacement is quieter and mine works fine after replacing it 4 years ago.
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
So, following Oilhammer's suggestion, I checked the HPFP solenoid screen and it's clean as a whistle. No debris whatsoever. Put it back together, ran the VCDS priming procedure a couple of times, and still get limp mode and the same codes when trying to accelerate hard. As long vas I'm gentle, the car drives fine, even at highway speeds...

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1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
the good news art is the upgraded replacement is quieter and mine works fine after replacing it 4 years ago.
Were you going into limp mode and getting the same low rail pressure fault code? Thinking you might be right, because the VCDS priming operation takes well over a minute to complete.
 

thundershorts

Top Post Dawg
Joined
Jul 15, 2010
Location
west chester pa
TDI
2015 passat tdi sel premium 2015 golf s tdi gls tdi b5.5, 2002 eurovan,Peugeot 505 td,Citroen cx25 prestige
Tank lift pump failing causes low rail pressure. Replace it before it leaves you stranded somewhere. The new pumps are much better and very quiet
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
So, I called my cousin who is the parts manager for a local VW dealership today to see if he had the pump in stock. I described the issue to him and he put me on hold while he talked to the service manager. He suggested that I bring the car in so I did and, after checking it out, they said that everything will be covered under the extended Dieselgate warranty...
 

TurboABA

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Joined
Jul 24, 2010
Location
Kitchener, ON
TDI
RIP-2010 Jetta 6spd 2014 Touareg Execline
Everything will be covered when it fails... or you took it in with existing DTCs and they are "covering" it now?
 

adjat84th

Veteran Member
Joined
Dec 13, 2008
Location
Virginia Beach, VA
TDI
'01 Jetta TDI/'15 Golf TDI
Would be good to know what ends up getting replaced. I had a recent bout of low rail pressure codes at low rpm/high load request recently (though with CP3), and went straight to replacing the filter and then suspected the in tank pump. Was resolved with a tune update, but I'm still skeptical the tank pump could be getting tired.
 

thundershorts

Top Post Dawg
Joined
Jul 15, 2010
Location
west chester pa
TDI
2015 passat tdi sel premium 2015 golf s tdi gls tdi b5.5, 2002 eurovan,Peugeot 505 td,Citroen cx25 prestige
Mine kicked at 2k. If you follow the pump part numbers, you'll find there have been several revisions to the pump.
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
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2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
is-a-puzzlement.jpg

Well, I was out driving around today and thought I'd give it a go after driving like an old lady for the past week and guess what? No flashing GP light, no MIL, and no limp mode, just nice peppy acceleration...
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
Nothing was replaced. They didn't have the pump in stock. It fixed itself, just like the adaptive headlights on our Sportwagen...
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
Update. The limp mode with the same codes returned last month, but on the day before I was taking the train back up to RI, so I just left the car in the garage. (The Hatch stays in the garage at the house in Baltimore that we're getting ready to sell.) I made a reservation last week to bring it in for service today as I came back to Baltimore yesterday for a few weeks. It started right up, but the MIL was gone and there was no limp mode, but I drove it to the dealer anyway. They scanned it and found the past codes but, since it was driving okay, couldn't really do anything so I left. Not five miles down the road, BINGO, limp mode! Turned it around and limped back. I have a rental, and am waiting for the diagnosis...
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
Just heard from the dealer and they are "working with the VW engineers..."
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
I just got a call from the dealer and the "VW engineers" have determined that it needs a new HPFP. And, it's covered by the extended Dieselgate warranty!!
 

TurboABA

Top Post Dawg
Joined
Jul 24, 2010
Location
Kitchener, ON
TDI
RIP-2010 Jetta 6spd 2014 Touareg Execline
I would press them regarding the rest of the system components..... it doesn't take a lot to damage the injectors. At the very minimum, I believe the tank\lines need to be flushed. Make sure you get this in writing as "having been performed" so that if your injectors crap out in the future, you can blame it on them mickey mousing the HPFP fix.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
From talking with a Bosch guy (so, take this FWIW), the solenoid operated CR injectors are in general more robust than the piezo stack units are. The piezo ones will burn themselves out very quickly if debris gets into the pintle chamber. But since the solenoid injected CR TDIs run at a reduced rail pressure, is it that or a combination that we see far less HPFP failures on them?

Of course, the CKRAs tend to have injector problems all on their own, so who knows.
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
I would press them regarding the rest of the system components..... it doesn't take a lot to damage the injectors. At the very minimum, I believe the tank\lines need to be flushed. Make sure you get this in writing as "having been performed" so that if your injectors crap out in the future, you can blame it on them mickey mousing the HPFP fix.
As you can see in the photo above, there are no metal shavings or any other debris whatsoever on the solenoid screen or in the pump, so I doubt that's an issue, but I will definitely ask.
 

tdidieselbobny

Top Post Dawg
Joined
Apr 4, 2005
Location
Stafford,NY (WNY)
TDI
'03 Galactic Blue Jetta TDI, '15 Silk Blue Golf Sportwagen TDI
From talking with a Bosch guy (so, take this FWIW), the solenoid operated CR injectors are in general more robust than the piezo stack units are. The piezo ones will burn themselves out very quickly if debris gets into the pintle chamber. But since the solenoid injected CR TDIs run at a reduced rail pressure, is it that or a combination that we see far less HPFP failures on them?

Of course, the CKRAs tend to have injector problems all on their own, so who knows.
The OP's car is a '15, so it's the CRUA, correct?
 
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