Error Code P0299: Turbo/Super charger underboost

**clemsongt** · 05-30-2009 09:14 PM

Error Code P0299: Turbo/Super charger underboost

So I got a check engine light last night after reaching about 5000 rpms (don't go that high too often) and took it to Autozone and got this code pulled. The description their computer put out for 'Volkswagen' is as follows:

Explanation:
Faulty wastegate bypass regulator valve
Probable cause:
1. Mechanical damage at turbo/super charger
2. Faulty charge Air pressure sensor

So all that I can glean from this is that it was caused by either the diverter valve or MAF sensor. Since I've heard that a torn DV doesn't usually throw a CEL, and that I didn't notice a loss in boost (don't have a gauge to exactly confirm it), that would leave the MAF. I don't have a K&N so no oil on the MAF from that.

He cleared the codes, and it didn't come right back, but on the drive home I didn't get too high in the RPM range, either.

Guy's have any thoughts?

PS: I guess the fuel injector cleaner he sold me after pulling code P2099 (fuel injector failure) won't help much...

...oh well guess it won't hurt to throw it in a tank.

EDIT: I figured if anyone found this while searching and wanted to know what was done in my case to resolve the issue it would make sense to add it. I took off my MAF sensor first as that is relatively easy to do and found no reason for it to have sent the code. Next I took off the DV and found a slight tear in it. The tear was not big enough to cause all boost to leak, but enough that at higher RPMs and higher boost, the computer would notice the leak. I ordered the new "D" revision diverter valve and put it on. After riding around and getting into higher RPM range the CEL has yet to return.

**shamrok** · 05-30-2009 10:03 PM

DV is usually the culprit, but not always. When mine failed though, the loss of boost was definitely noticeable.

**Chr1sJohnson** · 06-08-2009 02:36 PM

Hey did you ever resolve your issue? I am currently having the exact same problem. I took my car to GMP performance in Charlotte and their computer read CEL P0299.

My turbo doesn't seem to be boosting at all.

**SLYCAT** · 06-08-2009 02:55 PM

When my Forge DV was loose I got that code, not sure if this helps but it seems like a diverter valve issue. IMO

**djwimbo** · 06-08-2009 02:59 PM

Check the DV, otherwise it's possible to have a small boost leak.

Then again, my buddy just had his turbo replaced on his 2.0T FSI at 39K because it had a faulty wastegate.

Could be worth checking into.

**Chr1sJohnson** · 06-08-2009 03:05 PM

Originally Posted by djwimbo

Check the DV, otherwise it's possible to have a small boost leak.

Then again, my buddy just had his turbo replaced on his 2.0T FSI at 39K because it had a faulty wastegate.

Could be worth checking into.

Do you know what led to the faulty wastegate? I actually put 110 octane fuel in my car without knowing it contains lead. Perhaps the fuel lead to something more serious? My car runs perfect until I really get on it.. there is no boost what so ever.

**audifan22** · 08-09-2009 08:51 AM

Originally Posted by djwimbo

Check the DV, otherwise it's possible to have a small boost leak.

Then again, my buddy just had his turbo replaced on his 2.0T FSI at 39K because it had a faulty wastegate.

Could be worth checking into.

I had the same p0299 turbo underboost code and replaced the DV over a week ago with revision D, the p0299 code has come back, any clue as to what to look for next? That's the only code.

**clemsongt** · 08-09-2009 10:07 AM

You might have a boost leak elsewhere. If you have any way of doing a pressure check, I'd recommend that. The heater hoses that carry the air to and from the intercoolers could be at fault. The MAF sensor could also be at fault for reading incorrectly. This might happen if the MAF sensor was dirty.

If you have access to a full VAG-com and can run boost logs, you should be able to tell if it's actually a leak or a bad sensor.

**Stea1th** · 06-28-2010 07:55 AM

mine was a faulty wastegate

**viziers** · 06-29-2010 05:01 AM

I'm still getting my p0299 code to.. I'll try to check out my MAF and the DV is the latest piston driven one.....

vizi

**kag341** · 06-29-2010 07:03 AM

i just had this code with my 06 A4. ended up being a bad wastegate and the whole turbo assembly was replaced

**CystmX** · 06-29-2010 08:53 AM

I got the code about a month ago got it cleared and it hasn't came back on. However I would like to add that I don't feel the car drives the same since then. I've gunned it a couple of times and it just feels sluggish.

**bergy12** · 06-29-2010 09:17 AM

I've had this code for awhile now. Comes on when I go wot and usually clears after a few cycles. I've checked the dv and a few other things but still havnt found the problem.

**quickaudi07** · 06-29-2010 02:02 PM

I had mine for about 1 year now, and i have nothing but problems with my car. Also talked with people with APR and REVO, told me that these engine FSI 2.0T are piece of carp. That’s why Audi/VW replaced the engines with TFSI much better engine!!! I hope to get a better job and get rid of that piece of crap car. I spend crap load of money and time on it. Good luck with the codes. I have engine light on mine as well. But i just put tape over the gauge cuz i can’t stand looking at it anymore!.

**RickySlickUHS** · 03-10-2012 06:32 AM

I just had this come on yesterday and got the P0299 code. Checked the hoses and they looked fine (my car also went in a ditch

) so I figured it had to be the DV. Felt sluggish and went through 3/4 tank of premium in 240 miles! Luckily the stealership had the part on the shelf. Went and paid 125 (including tax) for the new revision D diverter valve. Since I'd already ripped off my belly pan it was easy to get to but those stupid nuts holding it on was a pain to get off. I read some conflicting information and used a Torx 30 to get them off, only to find that they were actually 5mm allen head bolts. I had to go buy a 2" 1/4" drive spacer to fit with my wrench and bit because the bit was too long. Anyways, got the old dv off and saw a small tear in the diaphragm, so that was the culprit. Thank God. Put the new one on and she runs like a sewing machine. And the tick-tick-tick I used to hear loud and clear has quieted down. Hopefully the gas mileage will improve but I haven't driven it much since. FWIW.

**vtruong88** · 07-31-2012 12:33 PM

got the P0299 code after upgrading ECU to stage 2. My DV was fine when I check it - had newer revision. No noticeable boost pressure loss.

What is the best way to diagnose this CEL?

**redlegs13m** · 10-13-2012 05:17 PM

does anyone know if a PCV failure will trigger the P0299 code I just had my DV replaced less then 6 months ago. I am getting noticeable suction under the oil cap while the engine is running, so from what I have read my PCV is toast. I also have the APR stage 2 flash but that was done over 2 years ago so I'm pretty sure that's not the culprit in my case.

**NODO-GT** · 10-14-2012 12:20 AM

Originally Posted by redlegs13m

does anyone know if a PCV failure will trigger the P0299 code I just had my DV replaced less then 6 months ago. I am getting noticeable suction under the oil cap while the engine is running, so from what I have read my PCV is toast. I also have the APR stage 2 flash but that was done over 2 years ago so I'm pretty sure that's not the culprit in my case.

^This

I had P0299 Code for some time. I deleted this error and after some hard driving it came back.
I knew my PCV was bad, because of oil cap being sucked in...
Went with BSH PCV Fix and problem is gone.

**redlegs13m** · 10-14-2012 06:33 PM

Originally Posted by NODO-GT

Went with BSH PCV Fix and problem is gone.

are you talking about the pcv plate or the catch can system.
i know there are a lot of options i'm just trying to figure out the most cost effective way to fix this that is not detrimental to my vehicle in any way.

**NODO-GT** · 10-15-2012 12:04 AM

PCV Fix is a plate option for about 90$.

**audiloverCA** · 12-03-2012 05:32 PM

Originally Posted by NODO-GT

PCV Fix is a plate option for about 90$.

Where did you purchase this? Have you seen a DIY?

**NODO-GT** · 04-06-2013 12:23 PM

Bringing an old thread back!
Again Problem is back... all mods in my discription.

I have noticed that whole winter I didn't get this code, but it came back as temperatures rides again. I comes at WOT....

I have no clue what to do, cleaned MAF, Replaced DV, Installed PCV Fix...
the only thing left wastegate? or are there any other options?

**seal66** · 04-06-2013 01:23 PM

good luck man. I have changed so much crap out trying to see why I still get the code. I still really only get the code in higher gears when I am doing like 4th and 5th gear pulls. I have yet to have it pop on me during logs pulls in 3rd, but it does pop up when I'm not logging, weird up lol. Damn car is grumpy man.

**Jhad** · 04-06-2013 02:57 PM

I've recently joined this club... I think i need to adjust the wastegate on the k04 after all the reading I've done on the subject. I am deciding if I should mess with it, or go with this.

Has anyone adjusted their wastegate or have any experience with forges wastegate?

**seal66** · 04-06-2013 03:49 PM

Look up jimrobbington. he did a wastegate adjustment had has a DIY in the tech forum n the B7 thread

**Jhad** · 04-06-2013 03:57 PM

Found it. Thanks Seal.
Most of the other threads I've found have been with vw's

**clemsongt** · 04-06-2013 06:02 PM

If individual components are not at fault for this code, it could just be that you have a boost leak in a hose somewhere - even a pinhole could be enough to trigger the code while not be noticeable in daily driving. The only way to diagnose that would be to do a pressure test. There are some DIYs out there on how to do this.

**NODO-GT** · 04-07-2013 12:57 AM

I want to do boost leak test.
Which test is better, smoke machine test vs pressure test?

I have option of paying 30$ for smoke test or building pressure tester myself...

I guess this tests will not show any problems with wastegate right?

I also have low MAF readings, could that be a reason for boostleak?

**mec** · 04-07-2013 01:09 AM

Originally Posted by NODO-GT

I want to do boost leak test.
Which test is better, smoke machine test vs pressure test?

I have option of paying 30$ for smoke test or building pressure tester myself...

I guess this tests will not show any problems with wastegate right?

It depends on what you want to do. Pressure test or smoke test will both get the job done. It won't have effect on yor wastegste because the pressure isn't enough to move it.

If you own an air compressor I would make the pressure testing tool. Jimeobbington has a nice write up on it. Otherwise if you want to save yourself some time just get smoke tested. Having your own tool is nice because you can diagnose quickly, you can work from home which is cheaper than the dealership/expensive shop, and after you sped the money on the supplies for the tool all you're boost leak tests will be free!

**mec** · 04-07-2013 01:11 AM

Originally Posted by NODO-GT

I want to do boost leak test.
Which test is better, smoke machine test vs pressure test?

I have option of paying 30$ for smoke test or building pressure tester myself...

I guess this tests will not show any problems with wastegate right?

I also have low MAF readings, could that be a reason for boostleak?

Tapatalk double post

**redfred** · 04-07-2013 05:11 AM

If you still have the original diaphragm style DV, I bet it's torn. Mine tore when downshifting to pass a schoolbus. The code cleared after replacing the DV with the new revised one.

Search, there are some good DIYs. BTW, I'd much rather have a bad DV than try to chase down a boost leak somewhere...

**frankvan** · 05-20-2013 01:53 PM

just got this code (0299) today while driving on the highway.
Cleared it and it has yet to come back, however my boost gauge is only showing a peak of 5 and holding at about 3.5 (yesterday it peaked at 15 and held at 13 psi).
DV? Wastgate? Intake leak?

**frankvan** · 05-20-2013 08:28 PM

Yup, dead diverter valve. One big tear (red) and pinhole tears forming (blue) where the rubber diaphragm "pinches" when it's compressed. Definitely a poor design.

**ducati** · 08-08-2013 02:55 PM

Im getting the code occasionally but when I reset aka removing a battery terminal then reinstalling it goes off for a few months..there is a slight lost in boost but not anything worrisome...Where in Canada can I pick a DV valve instead of a dealership...ordering from the US shipping is almost $25 plus duties.

**quickaudi07** · 09-10-2013 05:32 AM

I got this bad ass code this morning while driving on the high way in 4th gear. I hear that my turbo makes funny sounds when it goes down to idle, sounds like a rattle between 3.5k RPMS to 1200 RPMS, only when its about to idle at 700-800 rpms.
And while driving, i was to lazy to switch the gears and downshifting, decided to add more gas, well I didn't notice any leg like some of you guys, but engine light came on.

So I"m thinking, 2 things could go wrong or 3 lol,

PCV Valve, Divert Valve which i have the new Revision, or Turbo is about to take a dump! I"m at 88K miles on my car..

I haven't had real problems with the car for the past 2 years. now winter is coming and yea... shit is about to start!

BTW where can i buy OEM turbo?

**4rings5stars** · 09-10-2013 07:26 PM

I've had this issue ever since I went APR STG1. DV is brand new and I'm yet to perform a pressure test, so I can't rule out a boost leak. Other than that, I would be leaning toward the wastegate. I'll adjust it per the DIY when the time comes.

**quickaudi07** · 09-11-2013 06:06 AM

ON mine it sounds like it could be a bad turbo, I drove it this morning, and was looking on ODB II with tablet to see if any leaks or any odd things happening, and i couldn't find anything,,, it hits 15-16 PSI at full boost no issues... F-ing cars lol!

I will be looking at DV Valve to see if anything is wrong there...

I got APR STG1 as well, :)

**drumnjuny** · 09-11-2013 06:11 AM

brendan, haven't you been stage 1 for like ever haha??

i've had this code when i was stage 2, only started happening a year after i bought a tune for the car...

but i've had a boost gauge the whole time and it was really obvious that i was still hitting 21 psi

still happens today, a full engine build and BT later. no one knows what causes it

**quickaudi07** · 09-11-2013 12:05 PM

I have cleared mine yesterday and didn't show up even after few hard pulls... oh well F it, it it comes up back up, Ill just blow that car up :)

**jcr223** · 09-11-2013 12:06 PM

Most Likely a faulty waste gate If you have already replaced diverter valve, and concluded there is no boost leak. If you roll your passenger window down and let the engine decel you will hear a slight tapping noise, similar to a baseball card in the spoke of a bike as the RPM's wind down. I'm currently dealing with this as well....

I seek a new turbo .... :)