Hello,

 

I'm new here. I hope that posted in the correct forum.

My car is Octavia MKIII CR TDI 2.0 150hp, model year: 2014.
Millage: 63000KM (39375 miles)

Sorry, the post is going to be long. :)
If you want  to skip the story, please go to the summary.

The long story:

I searched for similar problems in the forum, usually error code P2563 seems to be resolved by  replacing VNT actuator, or cleaning turbo vanes.

In my car VNT actuator was replaced, but it did not solve the problem.

The problem happens only on cold start at morning, after about 30sec glow plug lamp starts flashing, cruise control gets disabled, and engine working in limp mode without turbo.
Restarting the engine always solves the problem and the engine pulls very well, I don't feel any degradation in power and fuel economy.

I checked error codes with OBD eleven, it shows: P256300 (7934).

First time when the problem happened, I went to the dealer right away, and they replaced VNT actuator with a new genuine part.

After about a week, I saw the problem again (on cold start at morning, after the car was not in use couple days). Restarted the engine, and the problem was gone.
The problem did not happen for a week.
Next week, on cold start the problem happened again (after the car was not used couple days). Restart solved the problem.

Starting from another week, this problem appears every morning on cold start.

I went to the dealer again, after diagnostics which lasted a day, they could not reproduce the problem.
They checked vacuum lines, sensors, VNT actuator and etc. All seems to work properly.

Now after consultation central dealership, local dealer decided to replace the turbo.
I'm waiting for the goodwill approval from the manufacturer to make this repair for free (the car is only one month out of warranty).

I drive the car in mixed conditions every day: climbing a hill on high speed, city driving and highway driving.
Usually I'm not flooring it, but I drive a bit hard and fast. My DPF regenerations happening about once per week.
Consumption is 5 L/100km (about 47MPG).

Summary:

 

1. OBD eleven, shows following error code: P256300 (7934)
2. Problem happens only on cold start at morning every day, engine works in limp mode (glow plug lamp is flashing, cruise control is disabled and turbo is not working).
3. Restart of the engine makes the problem disappear until the next morning. The problem never occurred during driving. Fuel consumption is fine and engine pulls very well like usually it does.
4. Previously the problem was happening once a week on cold start after the car was not in use for couple days.
5. After first time I saw the problem, dealer replaced VNT actuator. This did not solve the problem.
6. On the second visit to a dealer, after deep diagnostics they were not able to reproduce the problem (they checked vacuum lines, VNT actuator seems to move fine, sensors and etc.).
7. The dealer is going to replace the turbo.

 

Replacing the turbo seems a bit wired to me (because in case of soot in turbo vanes I would expect the problem to happen when driving, and also I think, according to the millage it is a bit early for soot problem to happen).

Any ideas what can I check and what might be the problem?
 

Thanks in advance.

Skoda aren't going to recondition the turbo, would have to go to a specialist for that. So its easier for them to change it.

I would not argue, you get a new turbo and hopefully it solves it.

How often has it had oil changes.

Old dirty oil might gum up the turbo vanes.

Hi,

Thank you for quick reply.

I'm changing the oil every 10,000km (6250 miles). I use Castrol Edge 5w30 which is recommended for my car by the manufacturer.

New turbo is always good, I absolutely agree.

But I have doubts about it, because the error comes on cold start and not during driving the car.

Anyway, once the turbo will be replaced - will let know if it solved the issue.

Thanks.

I also got glowing plug flashing the other day on cold morning, restart did fix the problem. And this is not the first time I got flushing plug which would disappear after restart or two (it did happened several times in last 2 years). Whatever it is on my car I hope it dies before the warranty runs out.

 

In which module you get the error in OBD eleven?

The error is in module 1 (engine).

In my case, the issue happens now every morning on cold start. First time it happened few days before the warranty was ended.

I recommend: hurry up with the issue and let know the dealer before the warranty ends. Computer records the error and keeps it for some time, but eventually after some successful starts without the error, it should delete the fault from the memory.

Also, once the engine is running in limp mode, it does not regenerate the DPF. It will be clogged in no time if keep driving in limp mode (in case of restart as temporary solution, it does regenerate when it is not in limp mode).

The vacuum feed supply line from the pump located in the sump has a one way valve in it - that valve is sticking and causing no vacuum accumulation, the pipe needs replacing.

No point messing about with the turbo.

Dealers will not do anything with just the error showing (I have not had limp modes so far). The car must break for them to do something.

Hi James,

 

Thank you for your reply.

On cold start, when I get the error, it happens every time after exactly 50sec (probably engine control unit has some timeout for vacuum build up).

 

Is there way to verify the vacuum valve?
I tried to test it today: after I got the error and driven about 3 minutes, turned off the engine and then pressed brake pedal about 5 times, until it became really hard (I assume the vacuum has gone and booster could no longer assist).
Then, I started the engine, but the error did not appear again.

Where exactly the pipe is located?

Thanks.

Edited 20 December, 20169 yr by netwalker

You can read a vacuum gauge on the pipe or press the brake pedal from the first cold start. If the valve is closed then the servo assist will not drag the pedal down.

Hi James,

I tried pressing the brake pedal on cold start. Servo assist does not seem to drag the pedal.

The pedal feels like usual on regular driving. If pressing the pedal hard, then it drags the pedal. But this is happening in all conditions. Is that fine?

The turbo was replaced by the dealer. The car returned with critically missing coolant and missaligned steering. Problem was not resolved - as expected. But with the new turbo car pulls much better on low rev.

Going tomorrow again to the dealer. It will be the fifth day with the car in the garage about the same issue.
This is very frustrating, the car is only two years old and was very well serviced in short intervals. :(

Will ask the dealer check the one way valve. It seems to be almost the last resort.

Any recommendations which steps needed for diagnosing the issue? Where need connect the vacuum gauge?

Can somebody provide me schemes where the pipe with the one way valve is located?

Thanks in advance.



 

Hi,

 

Problem has been resolved! It was cracked vacuum pipe from air intake tube (it is feeding G581 with vacuum via N75).

All, thank you very much for your help and support.

Mary Christmas and Happy New Year!!!

Hi,

 

Problem has been resolved! It was cracked vacuum pipe from air intake tube (it is feeding G581 with vacuum via N75).

All, thank you very much for your help and support.

Mary Christmas and Happy New Year!!!

How the dealer missed that fault beggars belief.

How the dealer missed that fault beggars belief.

Considering the first part of the test plan is a thorough check of the vacuum system...

On 26/12/2016 at 09:15, netwalker said:

Hi,

 

Problem has been resolved! It was cracked vacuum pipe from air intake tube (it is feeding G581 with vacuum via N75).

All, thank you very much for your help and support.

Mary Christmas and Happy New Year!!!

Is it possible to show me parts needed or pictures of it or something. I feel I have the same problem 

On 27/09/2021 at 23:01, Shasha said:

Is it possible to show me parts needed or pictures of it or something. I feel I have the same problem 

Old post I know but did you sort yours out or find what pipe the earlier poster mentioned? Thanks.