# P0299 Turbo Underboost



## tamorris2188 (Apr 30, 2012)

Recently had the CEL on and had the code read. It came back as an underboost code. I have looked for several posts regarding the issue with little results. Anyone know what the issue could be on the 2.0T TSI engine? Everything I have read has been for 1.8T or FSI engines. Any help and/or pictures on what to look for is appreciated. 

Also if you know of another post to check that would be helpful too. Just can't seem to find any clear answers for the CC.


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## BsickPassat (May 10, 2010)

It could DV or... check around for boost leaks from starting from the turbo to the throttle body.


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## tamorris2188 (Apr 30, 2012)

Thanks,

I am going to start checking things tonight. I just swapped out the old plugs and the ignition coils due to misfires and now I have a turbo under boost. Really quite a pain.


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## jkeith72 (Feb 14, 2011)

tamorris2188 said:


> Thanks,
> 
> I am going to start checking things tonight. I just swapped out the old plugs and the ignition coils due to misfires and now I have a turbo under boost. Really quite a pain.


 What year is your CC? It may have the older style diverted valve, that is prone to torn diaphragms. If it tears, that will cause a low boost condition...triggering a CEL. 

Checking what version valve you have is as easy as getting the part number off your existing valve. There are a couple of YouTube videos on VW diverted valve replacement. 

Hope this helps. Good luck! Please let us know what you find.


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## snobrdrdan (Sep 10, 2008)

^^^ 
And to elaborate on what he said, you can upgrade to the piston style diverter valve which "should" never fail....unlike the rubber diaphragm ones 

http://www.ecstuning.com/Volkswagen-CC-FWD-2.0T/Engine/Intake/Diverter_Valve/ES263879/


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## DasCC (Feb 24, 2009)

Turbo broke man!


Sent from my iDevice


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## tamorris2188 (Apr 30, 2012)

I have a 2009 CC Sport 2.0T. Any pictures as to where the DV is exactly? This is my first turbo engine. CEL came back on and it was the same code.


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## snobrdrdan (Sep 10, 2008)

tamorris2188 said:


> I have a 2009 CC Sport 2.0T. Any pictures as to where the DV is exactly? This is my first turbo engine. CEL came back on and it was the same code.


 If you jack up the passenger side of the car and look above the driveshaft, you'll see it (3 allen head bolts hold it on & with a harness connected to it)


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## tamorris2188 (Apr 30, 2012)

Thanks! I was actually under the car last night and did find it. Going to order the new part and gamble on whether or not it is actually the problem. Try replacing that. Will check the diaphragm part to see if there are cracks, but at least I will know the new piston driven component is in there. 

The part is a pain to get off. My electrical clip harness on there does not want to budge off there.


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## tamorris2188 (Apr 30, 2012)

One other thing. Any ideas if for some reason it isn't the DV what else it could be? I have read the waste gate valve and was wondering what the cost of that repair would be? 

I can swap the DV myself probably, but anything more substantial under there I may not be able to do.


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## tamorris2188 (Apr 30, 2012)

*Replaced the DV*

I finally got the new DV from ECStuning.com and replaced the old one. The old part was covered with burnt on oil or something. I took a gamble on this too since it is an inexpensive part to swap and pretty easy to get off and back on. Hardest part was the dang wire harness clip. I was pleased right away when pulling the old one off to see a large hole in the diaphragm and know that this was most likely the problem. CC seems to be running much better after installing the new piston driven valve. I will try to post a pic of the old part in the coming days.


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