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I had mine checked out at the dealer after reading several threads all with different results of what was causing the issue thinking I could save money not having to get the cover or anything else. sucked having to pay the fee for diagnosis but it just end up having some ground terminals cleaned which is what someone else had done before as well. Been good ever since. I don't know which ones they were but maybe it'll be enough to point you in the right direction since you think it could be electrical.
So after clearing the CEL about 2 more times after I replaced the valve cover, it looks like the fault code is staying away (for now). Very strange that it didn't clear right away but I was able to run over and pass my emissions test without issue and I've put a few hundred miles on the car since then without the CEL coming back.

There's a grounding point on the back of the valve cover that looked ok to me but made sure it was nice and tight after I replaced it. After looking over the wiring diagram I don't think that ground has much to do with the actual PCV or emissions system but I am also not an expert at car electrical stuff so I could be missing something. Sounds like from your visit to the dealer that it would be good to look over the main grounding points in the engine bay to see if there's any other spots that could become an issue.
 

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Looking to bring this thread back to life. I just started getting the P04DB (in the cold weather). I checked the turbo inlet pipe for a sensor and cannot find one. I reviewed all the diagrams associated with the turbo inlet and do not see a sensor. Does someone have a part number for this part that was replaced? Also as far as the ground locations go, not sure if anyone has more information where they are so I can try to clean/tighten them first. It appears there are a few root causes to this code other than gasket replacement, that I would like to try first. I do not see any oil leaking out from my valve cover gasket so I am hoping that is fine, car has 45000 miles. I did just have the water pump replaced due to leaking, I think the two issues are separate though. I see you can just buy the gasket instead of the entire valve cover, which is significantly cheaper ($80 verse $500 https://www.audihendersonparts.com/...ION-MOUNTS-PISTONS-RINGS--BEARIN/F214055.html). Any other things to check would be greatly appreciated!
 

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Looking to bring this thread back to life. I just started getting the P04DB (in the cold weather). I checked the turbo inlet pipe for a sensor and cannot find one. I reviewed all the diagrams associated with the turbo inlet and do not see a sensor. Does someone have a part number for this part that was replaced? Also as far as the ground locations go, not sure if anyone has more information where they are so I can try to clean/tighten them first. It appears there are a few root causes to this code other than gasket replacement, that I would like to try first. I do not see any oil leaking out from my valve cover gasket so I am hoping that is fine, car has 45000 miles. I did just have the water pump replaced due to leaking, I think the two issues are separate though. I see you can just buy the gasket instead of the entire valve cover, which is significantly cheaper ($80 verse $500 https://www.audihendersonparts.com/...ION-MOUNTS-PISTONS-RINGS--BEARIN/F214055.html). Any other things to check would be greatly appreciated!
After I had to re-visit this issue and looked into it a bit more, I just could not figure out what exactly on the turbo inlet would cause this CEL and I think I was actually given either bad or wrong information the first time I had to deal with this. Unfortunately, so much time has passed that I don't think I'll ever know. Plus, even having the service manual for this car it's kind of impossible to troubleshoot this CEL because of the way the PCV system is designed and completely integrated into the valve cover. Crazy enough, replacing my valve cover on my current TTRS seemed to fix the issue and I was able to find one on sale before the holidays for about half price.
 

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Ok, so I guess the issue is more around the cover itself getting damaged then the gasket leaking? The Audi dealership in Nevada seems to have the best pricing right now on parts that I see. Not sure who you bought from.
 

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Ok, so I guess the issue is more around the cover itself getting damaged then the gasket leaking? The Audi dealership in Nevada seems to have the best pricing right now on parts that I see. Not sure who you bought from.
Pretty much the whole PCV system is "integrated" in the top of the valve cover. The tech articles simply state that if the ECU thinks anything is wrong with any part of this whole system, it will throw a code and since it's all one piece there's not much troubleshooting you can actually do.

I bought my cover from Audi parts USA before the holidays, they had like a 40% off and free shipping deal for a couple weeks and snagged it then.
 

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Here's a test. :eek:

The next person that has an issue with this error code try;

#1 There is a ground bridge / jumper/ wtf ever you want to call it, located on the back of the valve cover. Try removing these two screws and cleaning the contacts by scraping them sideways with razor blade. I've become proficient at this method, you can try, or 220 grit sand paper should be okay too. Clean the bottom surface of the screws with a wire brush. Apply die electric grease to the terminals, screws, brace / jumper, all over the place and reinstall that assembly. It's super easy to strip those screws. Reset the computer with your hand held scanner and drive it. If you have the cheapy scanner please use that, that way folks that have the cheapy one can participate in the inexpensive way to fix it without having to buy the 10 thousand dollar scanner to clear codes. Give it what a hundred miles or so to see if it solves the issue?

If not then please try this next. If you do both of these, then we won't really know the definitive cause here...

#2 Add seafoam into the engine. Follow the directions yadda yadda. I know a lot of folks have claimed to change just the filter and not the oil, and it still has all of it's viscosity, blah blah blah. Don't be such a cheap ass, and change it every 3k miles at the max. Less if your hard on your driving.

Post your findings please. I know of several folks out there who have a ton of miles on their cars and have never swapped out the valve cover. :peace:
 

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So, I guess I was the "next person" to have this code. It popped up about 2 weeks after an oil change. There was too much oil, but I'm not convinced that was the cause. I cleared the code multiple times, removed some oil, and tried changing the diaphragm under the black cap on the valve cover. The code kept coming back.

After removing the valve cover to try the above suggestions, I realized it was such a pain in the ass that I wasn't gonna do it again. So, I ordered a new valve cover...aka nearly $600 PCV valve. A week later I reinstalled it. That was a month ago. No more codes. I'm convinced you just have to bite the bullet. FWIW, the valve cover is so annoying to remove. I'm tempted to take the old one apart to investigate, but have been lazy about that.
 
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I just had the code appear after a turbo installation done by a local garage. Removed the turbo air inlet hose to take a look at the ground wires, one (on the left facing engine) was definitely loose. It's a little difficult to access unless you have a mini Kobalt ratchet and a 25mm torx. I removed both ground screws, re-tightened the screws firmly and deleted the code. Road test confirms code is now gone, so yes, if one or both of the ground screws on the back of the cover are loose, it will set a code. Mine was "Crankcase ventilation System, P04DB-08-disconnected". Hope that info helps.
 

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I just had the code appear after a turbo installation done by a local garage. Removed the turbo air inlet hose to take a look at the ground wires, one (on the left facing engine) was definitely loose. It's a little difficult to access unless you have a mini Kobalt ratchet and a 25mm torx. I removed both ground screws, re-tightened the screws firmly and deleted the code. Road test confirms code is now gone, so yes, if one or both of the ground screws on the back of the cover are loose, it will set a code. Mine was "Crankcase ventilation System, P04DB-08-disconnected". Hope that info helps.
Can you post a picture of the ground wires you tightened?
 

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I just had the code appear after a turbo installation done by a local garage. Removed the turbo air inlet hose to take a look at the ground wires, one (on the left facing engine) was definitely loose. It's a little difficult to access unless you have a mini Kobalt ratchet and a 25mm torx. I removed both ground screws, re-tightened the screws firmly and deleted the code. Road test confirms code is now gone, so yes, if one or both of the ground screws on the back of the cover are loose, it will set a code. Mine was "Crankcase ventilation System, P04DB-08-disconnected". Hope that info helps.
My error did NOT have the "-08-disconnected" part. And the wires were NOT loose.
 

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My error did NOT have the "-08-disconnected" part. And the wires were NOT loose.
Same for me when I had the issue. My connections were all good too and replacing the valve cover was the only way to permanently get rid of the CEL. It seems though if you have "disconnected" appended to the error code then maybe a simple check of the ground connections is still a good first step to check and may clear the issue instead of wasting money on another valve cover.
 
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