Fuel rail pressure issues (limp mode; P019100 error) - at my wit's end after multiple major component replacements with no luck. What next?

[Gabs238]

've owned a petrol 62 reg Skoda Rapid (1.2 TSI) for almost 18 months now. I'm having repeated fuel rail pressure issues and it's starting to drive me (and my local garage) nuts, so I'm turning to Briskoda for some help.

2022 October - broke down on the motorway due to a cylinder misfire. Turned out to be a faulty HT lead; out of precaution (as I'd bought the car used), I got all HT leads, all spark plugs, and coil pack replaced.

2023 Mar-May - a couple of instances where the car loses acceleration and enters limp mode, but is immediately fine after stopping in services and restarting the engine. Didn't investigate further. Starts to idle rough and mildly shake whilst driving, but difficult to tell if actually a new issue or just never noticed.

2023 Sept - loss of acceleration (limp mode) + EML + EPC light. I'd bought a basic OBD reader by this point and it was giving the following errors:

Charge pressure actuator. P334B00
Fuel Rail Pressure Sensor "A" Circuit. P019100

Garage diagnosed it as faulty turbo wastegate actuator (with the fuel rail pressure fault as a result of trying to compensate for turbo issues), had a new one fitted.

2023 Sept - after having the car back a few days, same issue (loss of acceleration + EML + EPC light), but this time only giving the fuel rail error code. When it does run, it idles really roughly, and sometimes just dies at red lights. Garage try to diagnose issue; no luck, so they get autoelectrician in. Autoelectrician points to the high pressure fuel pump being faulty, they replace it.

2023 Oct - after having the car back a few days, it's obvious that the rough idling has immediately been resolved, no dying at red lights, and no entering limp mode randomly anymore, so I thought we'd finally cracked it. A few days later, limp mode + EML + EPC light... I take the car back to the mechanic and at this point they have no idea what's wrong. They got the autoelectrician back who couldn't find any issues. They tried a new fuel filter but still same issue when they did a long test drive. They're waiting on a quote from Skoda on a new low pressure (lift) pump, but were open in saying that at this point it's just pure guesswork trialling new components, and it's up to me how far I want them to take it.

Now - It's driving me nuts as it's an intermittent error and otherwise the car drives beautifully for its age, but I'm at my wit's end. The car cost me ~£4900 new in June 2022 (~78k miles) and I've had to spend over £1300 on these turbo + fuel system issues so far in the last couple of months, with no solution on the horizon, having only driven it 12k miles (including servicing).

1. Should I also ask to have the fuel rail pressure sensor itself changed just in case it's faulty, despite showing up as OK when examined by the autoelectrician?

2. If neither LP pump replacement nor sensor replacement work, what would be the next steps? Are there any other components to replace in the fuel system? Are there any other known problems (from outside the fuel system) that could cause this error code and these symptoms? Do I take it to a Skoda specialist?

3. At what point do I call it quits and get rid of it despite being an excellent budget car? It seems like a phantom issue and it seems insane to take a big loss selling what is otherwise a car which is in great nick, but at the same time if a new LP fuel pump and new sensor don't fix it, I'm starting to worry this won't ever get resolved.

Any advice, comments, etc. would be gratefully received. Thanks!

[inspectorman]

Fuel rail pressure sensor definitely worth doing. Since it's an intermittent fault it may have been behaving when the auto electrician was looking. One of these small Skoda engines does have issues with the fuel manifold ( ?) Coming loose but you've had enough mechanic time on this for it to have been spotted.

[Breezy_Pete]

Unplug the electrical connector from the fuel pressure sensor and see if there's any fuel inside the connector. That might be a giveaway for a failing sensor.

[Gabs238]

Thanks both, much appreciated! One thing I've come across online this evening is that an old battery can cause strange symptoms on Octavias, even when fully charged. Is it possible this applies to Rapids too? I haven't a clue how old my battery is, but it may be pretty ancient.

 

inspectorman: That makes sense, I'll ask them to replace the sensor too. On the off chance it's the wiring / connector that is faulty and not the sensor itself, how is something like that normally dealt with? Is it hard to have tyat wiring replaced? In terms of the fuel manifold, that's good to know! As you say, hopefully has had enough mechanic time to be spotted, but always good to be aware of it.

Breezy_Pete: I'll give that a try. I assume fuel inside the connector would imply a physical/mechanical failure of the sensor, which could cause the intermittent fault? I suspect this would have been spotted by the auto electrician when checking the sensor, but I'll check the connector myself when I get the car back after the LP fuel pump replacement.

[Kostas123]

The simple truth is that if the repair shop is out of ideas and simply wants to shotgun replace all related parts, you really need a different shop (hopefully one that is better).

[Gabs238]

Thanks Kostas123! I tried to summarise it very briefly so I haven't been able to completely do them justice. They've been very transparent throughout the whole process and I feel like replacing the LP fuel pump is still a worthwhile endeavour, so it's me who is asking them to go ahead with it, but if it doesn't work then I'll try a new garage.

 

The current one is a 2 min walk from my house and have spent a lot of time on the car so I've tried to stick with them for now, but I'll take the car to a Skoda specialist as a next step.

[Kostas123]

At least from the manual for my engine (which is different), limp mode is entered when the high pressure pump fuel dosing valve fails, then it revers to the fuel pressure control valve within the fuel rail itself (my engine uses common rail), however the failure of the low pressure fuel pump would make the engine quit completely. Of course there are many other factors that could lead to the the low pressure pump being the culprit after all, however almost every single diagnosis can be made without spending money on parts provided that the person diagnosing understands how the system works and has time to think and verify things.

So either the place you are going to services way too many vehicles for them to actually get to know any of it, or they simply want you out of the door as soon as possible. Neither is OK.

Edited 24 October, 2023 by Kostas123

[MickA]

I mention this anyway although yours is pointing to a fuelling issue.

My Toledo (same engine) threw an EPC light up and also went into limp mode.  After a few times of this happening it eventually threw up an engine management light too.  Fault diagnosis (my simple tool) throttle position sensor fault. Garage confirmed this when plugged in but not convinced this was the fault. Anyways other checks done and eventually and very quickly they discovered a low battery, the battery wasn't in fact holding a charge. New battery fitted, all good.👍

Garage has seen problems with VAG engines before throwing codes up and then showing unrelated codes to the actual problem. Telling me that the battery needs to be in a decent state to receive and send back signals to the cars systems to say all ok. An uneducated explanation of what he told me. Also for info my car is stop/start so need a more heavy duty battery.

Maybe nothing to lose to get the battery checked but maybe a long shot.

Edited 24 October, 2023 by MickA

[Gabs238]

12 hours ago, Kostas123 said:

At least from the manual for my engine (which is different), limp mode is entered when the high pressure pump fuel dosing valve fails, then it revers to the fuel pressure control valve within the fuel rail itself (my engine uses common rail), however the failure of the low pressure fuel pump would make the engine quit completely. Of course there are many other factors that could lead to the the low pressure pump being the culprit after all, however almost every single diagnosis can be made without spending money on parts provided that the person diagnosing understands how the system works and has time to think and verify things.

So either the place you are going to services way too many vehicles for them to actually get to know any of it, or they simply want you out of the door as soon as possible. Neither is OK.

 

Good info, I really appreciate it! I'll take that into account and will see whether I can get a Skoda specialist to look at the car, as it sounds like they may be better suited to diagnosing this issue.

 

12 hours ago, MickA said:

I mention this anyway although yours is pointing to a fuelling issue.

My Toledo (same engine) threw an EPC light up and also went into limp mode.  After a few times of this happening it eventually threw up an engine management light too.  Fault diagnosis (my simple tool) throttle position sensor fault. Garage confirmed this when plugged in but not convinced this was the fault. Anyways other checks done and eventually and very quickly they discovered a low battery, the battery wasn't in fact holding a charge. New battery fitted, all good.👍

Garage has seen problems with VAG engines before throwing codes up and then showing unrelated codes to the actual problem. Telling me that the battery needs to be in a decent state to receive and send back signals to the cars systems to say all ok. An uneducated explanation of what he told me. Also for info my car is stop/start so need a more heavy duty battery.

Maybe nothing to lose to get the battery checked but maybe a long shot.

 

Interesting, thanks for sharing! I'll flag the battery idea up as one potential avenue to look into then, it sounds like it wouldn't be far fetched for it to be an issue then. "Telling me that the battery needs to be in a decent state to receive and send back signals to the cars systems to say all ok." certainly seems to make sense to me.

[Kostas123]

Don't limit yourself to Škoda specialists only, many VAG cars including Audi, VW and Seat also use the same engine and thus those places should also offer diagnostics to you.

[Gabs238]

1 hour ago, Kostas123 said:

Don't limit yourself to Škoda specialists only, many VAG cars including Audi, VW and Seat also use the same engine and thus those places should also offer diagnostics to you.

 

Thanks, I hadn't realised Seat were also part of VAG, I thought it was only VW and Audi. I'll broaden my search accordingly.

[MickA]

Just to add to this topic having re-read what you said is happening. Obviously first off get your battery checked or do as I've done since last year and acquired a simple but effective little gadget below. I think everyone should have one in their toolbox, it's saved me a couple times in messing with garages but my problems easily solved. 

 

https://www.ebay.co.uk/itm/372436652444?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=vrAwd99DT4i&sssrc=4429486&ssuid=PjrX0wOKTfG&var=&widget_ver=artemis&media=COPY

 

Around 5 weeks ago I stripped my door weather strips off for cleaning. The fronts needed the door card removing. During the process the cars windows were operated quite a few times up down on all four windows plus I had the ignition on off a few times and the radio on. The car had stood a few days before and after the event. Eventually I drove the car and after around 5 miles or so the EPC light came on. A mystery why, I diagnosed myself with the tool above, low battery. Charged the battery and all ok. 

I also whilst the EPC light was on, I used a code reader, no codes found though. It kept reappearing on driving a few miles. Since battery charging no more code thrown up 👍

Worth buying just for those checks and keeping an eye on the battery condition now winters approaching.

[J.R.]

You are almost certainly right in the fault being low battery charge related but if you were to invest in something like VCDS in the same way that you have on a decent battery tester (I also have one) you would almost certainly find the fault codes, likely to be low Terminal 30 voltage and communications failure with one or more Canbus modules due to the low battery voltage and a high load event like the power steering.

 

5 miles should be more than enough to recharge even the flattest battery, you may have something else going on, a worn alternator or a fractured excitation wire.

[Gabs238]

**RESOLVED**

 

I thought I'd post an update for the benefit of those who helped me, as well as anyone Googling this in the future looking for a solution.

 

In short, replacing the LP fuel pump and replacing the battery fixed the problem. The LP pump was just a guess but at this stage I was happy to invest the money, and the battery diagnostics initially came back fine (67% life, no issues, mechanic said he didn't see a reason to replace it), but once I explained my issues with the battery draining rapidly after a few days of no use, he said it may be a case of some faulty cells. As a new battery is pretty cheap, I asked him to go ahead and replace my old one with a brand new one.

 

The car runs great again, including starting much quicker, and crucially no more fuel rail pressure sensor faults (having done 600-700 miles now since the new LP pump and new battery).

 

The main thing that I would do differently next time is to immediately replace the battery when buying a ~10 year old second hand car - it would have avoided some battery issues over the past 3-4 months, and would have also helped pinpoint any other faults more quickly by eliminating the battery as a potential source of issues.

 

Thanks again for all the help and input, I really appreciate it!

[Warrior193]

9 minutes ago, Gabs238 said:

**RESOLVED**

 

I thought I'd post an update for the benefit of those who helped me, as well as anyone Googling this in the future looking for a solution.

 

In short, replacing the LP fuel pump and replacing the battery fixed the problem. The LP pump was just a guess but at this stage I was happy to invest the money, and the battery diagnostics initially came back fine (67% life, no issues, mechanic said he didn't see a reason to replace it), but once I explained my issues with the battery draining rapidly after a few days of no use, he said it may be a case of some faulty cells. As a new battery is pretty cheap, I asked him to go ahead and replace my old one with a brand new one.

 

The car runs great again, including starting much quicker, and crucially no more fuel rail pressure sensor faults (having done 600-700 miles now since the new LP pump and new battery).

 

The main thing that I would do differently next time is to immediately replace the battery when buying a ~10 year old second hand car - it would have avoided some battery issues over the past 3-4 months, and would have also helped pinpoint any other faults more quickly by eliminating the battery as a potential source of issues.

 

Thanks again for all the help and input, I really appreciate it!

Great news that you got it resolved.