Strong vacuum on oil cap while engine running - normal? Throwing PCV code

[Tom Sawyer]

I'm trying to determine if it is normal for there to be a fairly strong vacuum on the oil cap while the engine is running on our 3.0T engines. I'm getting one, takes a bit of force to take the cap off while the engine is running.

I'm asking because I continue to throw the following code for PCV valve (even though the dealer claimed to have replaced it, but definitely not done since the supercharger was not removed). From everything I've read, that is required to change the PCV. Setting up another appointment tomorrow, but wanted to try to have as much info as I can get before calling. Here's the code I throw... appreciate any info you can give. If someone can just try it and see, would be appreciated... just don't want to tell the dealer it's pulling strong crankcase vacuum if it supposed to be.

1 Fault Found:
20136 - PCV Valve Malfunction
P052E 00 [096] - -
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 3
Mileage: 77734 km
Date: 2018.12.31
Time: 11:40:24

Engine speed: 701.00 /min
Normed load value: 12.2 %
Vehicle speed: 0 km/h
Coolant temperature: 71 °C
Intake air temperature: 19 °C
Ambient air pressure: 1000 mbar
Voltage terminal 30: 14.624 V
Unlearning counter according OBD: 38
Engine speed: actual: 704 /min
MAF_ENVD: 119.83529 mg/stroke
Coolant temperature (unfiltered): 71.25 °C
Engine: operating status: IS
Engine load: 12.109375 %
Vehicle speed: actual: 0 km/h

[theweebabyseamus]

Textbook PCV failure.

[mikedizzzo]

My dealership just replaced the PCV hose. Car has around 41k miles on it. I threw the same codes as you and thought it was the PCV but they said it was the PCV hose


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[mikedizzzo]

And yes I did the vacuum test and it felt strong


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[Tom Sawyer]

Thanks, that is very helpful! I've got about 1.5k left on warranty, so not sure if they just blew the repair off or what, but the invoice states they did replace the PCV though it's pretty obvious they did not. Either way, at least I know the vacuum should not be there (or at least not as strong as it is).

It's a bummer though, was doing a full scan for codes before doing a stage 1 + DSG tune. Will have to wait on that now.

[Tom Sawyer]

I took it in first thing this morning and it was ready this afternoon after work. They confirmed the 3+ throws of the PCV code and this time they replaced the PCV valve along with the PCV tube (06E-103-207-AP). Very obvious the supercharger ('compressor' on the invoice) was pulled. All looks well and running smoothly. Glad to have this issue addressed 'under the wire' on the warranty.

[GandalfTheIbis]

For future reference, with a healthy PCV the oil cap takes about 2lbs of force to remove. With bad components in the system I find it closer to 8lbs.

[Tom Sawyer]

For future reference, with a healthy PCV the oil cap takes about 2lbs of force to remove. With bad components in the system I find it closer to 8lbs.

I agree 100%, gave it a try this morning after fully warmed from the commute and it was noticeably easier to remove. Quite relieved, that heavy of a vacuum can not be good on oil circulation. Now I feel ready for new plugs and loading in my new EPL tune!

Thanks again for the replies and info, greatly appreciated as always!

[dcchristopher]

This is interesting. I was recently in the Ross-Tech tool for basic maintenance purposes and noticed the P052E was thrown in December (and for a possible fourth time). One thing I've noticed with everyone's scan results is that the engine speed at the time is consistently under 1000 (so, at idle).

Flashback to the last time I was at the dealership (about a year ago) ... I was told there was an ECU update for an error code that would be thrown from time to time even though there was no real issue. The ECU update would basically prevent the code from being thrown in the first place (changing the thresholds, etc.). I'm _pretty sure_ it was intake-related so possibly PCV. The reason I opted not to get the update was that I have an APR tune I'd rather not lose.

[Phenotis]

I have a fairly strong suction on mine as well when I open the oil cap with the engine on. I thought they were supposed to be fixed on the CREC engines, but I'm not so sure.

Mine isn't throwing a code however. Has anyone had this happen with their CREC engine?

[Smac770]

What actual crankcase vacuum are you measuring (vacuum gauge on the dipstick tube)? CRE/CGX/CTU 3.0T (as well as those older CCAA/CCBA which have the oil consumption modification) should be running 150 mbar, iirc, (4.4 inHg). If you're measuring closer to intake manifold idle vacuum, then it would seem your oil separator regulating valve diaphragm tore.

A PCV can fail. There's always a statistic no matter how reinforced they might make things. The PCV has been through several revisions, even for CRE (now rev AF) and CGX/CTU (now rev AH).

[Indyhntr]

Bringing this back up as it is first web link in my search.
Have a 2013 A7 3.0t I just bought. I noticed it has strong suction at oil cap. I have two 2012 A6’s with same engine. Neither have this strong suction.
Read above reply’s, but I just did a complete under Supercharger refresh, everything from PCV, Thermostat, injector clean, carbon clean, new thermostat hose front to back, cross over pipe and breather hose (used second pipe plug from original breather) .
It still has vacuum. Ideas? I know bad-new part always possible.

- - - Updated - - -

Bringing this back up as it is first web link in my search.
Have a 2013 A7 3.0t I just bought. I noticed it has strong suction at oil cap. I have two 2012 A6’s with same engine. Neither have this strong suction.
Read above reply’s, but I just did a complete under Supercharger refresh, everything from PCV, Thermostat, injector clean, carbon clean, new thermostat hose front to back, cross over pipe and breather hose (used second pipe plug from original breather) .
It still has vacuum. Ideas? I know bad-new part always possible.

[LowKeyLoki]

As mentioned earlier you need to measure the vacuum at the dip stick to confirm what idle vacuum is at, possible you didn’t install the correct PCV pn# revision. What was the part number to the PCV you installed?

[A4Qwattro]

I concur with above. There are two PCV systems available. Depending on the production date of model, it may have come with the 30mbar PCV or a 150mBar PCV (more vacuum).

What is the part number on the pcv that you just replaced? Your 2012 3.0Ts most likely have the 30mBar version but the 2013 has the 150mBar version so more vacuum is expected. There's no reason to think anything is wrong especially if there are no codes, car runs normally, and it's a new PCV.

[Smac770]

All B8.5 3.0T (MY13+ in the US; CGXC / CTUB) should be the 150 mbar unit. All B8.0 3.0T (MY10-MY12 S4 sedan and S5 cabriolet in the US; CCBA) should be the 30 mbar unit, unless updated for oil consumption. https://static.nhtsa.gov/odi/tsbs/20...81642-0699.pdf As to why the 150 mbar used to replace the 30 mbar is different from the 150 mbar on the CTUx engines, https://www.audizine.com/forum/showt...1#post14907186

[Nillious]

There are so many threads about this where people are just saying their oil cap has strong suction. Especially the 150mbar version will have what feels like strong suction. “Strong suction” is very subjective. Any time you want to know if it’s operating correctly you need to measure the vacuum. I’ve also read a few times people thinking that the vacuum is the reason for oil consumption. Vacuum on the crank case is a good thing. When the diaphragm is torn (the reason for too high of vacuum) it Also let’s boost pressure into the crank case which is a very bad thing.

Another thing to note is very bad oil leaks or bad seals in extreme cases can throw a pcv code even though the actual valve is fine. Make sure your engine is sealed up the way the the program of the ecu is expecting it to be.

[vaa4]

Hope it helps someone, I went through all the troubles of replacing PCV after error 20136 was thrown. It didn't fix it as there is one more component to it.

Turned out, it was the Crankcase Breather Hose (06E103207AP), more specifically the solenoid that comes with it, that was malfunctioning.
15 minute job, all easily accessible under the hood, splicing into the original hose using 5/16 ID fuel hose with 2 clamps bought on Amazon.
Less than $100 - can't beat that. Dealership charged me more for "diagnosis", claiming they could not see the code and all is well.

https://www.fcpeuro.com/products/aud...ne-06e103207ap

[Indyhntr]

I concur with above. There are two PCV systems available. Depending on the production date of model, it may have come with the 30mbar PCV or a 150mBar PCV (more vacuum).

What is the part number on the pcv that you just replaced? Your 2012 3.0Ts most likely have the 30mBar version but the 2013 has the 150mBar version so more vacuum is expected. There's no reason to think anything is wrong especially if there are no codes, car runs normally, and it's a new PCV.

Sorry for late reply, didn’t get message of a response.
I checked production date of car and bought what FCP recommended for “after” that production date, which is the 150PSI unit. Did not think that the two different p/n’s would have different results. Thanks for that feedback.