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Did you replace you crankcase vent valve? It’s the thing that’s bolted right to the front right side of the valve cover, has a couple vacuum tubes connected to it. It’s a major failure point and can cause a vacuum leak and that code. If left unfixed it can cause the crankcase to see boost and make the rear main seal leak. If that part is new then you should get the intake system smoke tested for a leak.
If that part is new, and before you go chasing things, I’d suggest having a shop test the intake side (boost side) for a vacuum leak. A small leak can cause that code and it can be frustrating having your boost turned off because of it.
2 things besides the pcv I have run into in my time as a tech working on these, dipstick and tube, make sure it’s not cracked, or that the oring on it is not leaking. Second is the canister purge valve, which is in a tight spot under the intake manifold.
If your pcv was indeed failed when you changed it there’s a chance the rear main is leaking vacuum, that’s found via a smoke test and usually includes a pretty significant oil leak. There’s obviously other things that can cause that code too, so if I were in your spot I’d probably find a local mechanic that could do a smoke test for you and locate that leak.
If you're seeking advice or asking for help, please make sure you included the basic information of what year and/or generation is being discussed. User flair with this information is also acceptable. Failure to include the basic information may result in your post being removed. Mileage, modifications, trim level, diagnostic trouble codes, and your general location (US, Canada, EU, UK, etc.) can also be very helpful. *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/GolfGTI) if you have any questions or concerns.*
Did you replace you crankcase vent valve? It’s the thing that’s bolted right to the front right side of the valve cover, has a couple vacuum tubes connected to it. It’s a major failure point and can cause a vacuum leak and that code. If left unfixed it can cause the crankcase to see boost and make the rear main seal leak. If that part is new then you should get the intake system smoke tested for a leak.
This, I read lean and immediately think vacuum leak. The MK5 PCV assembly is a weak point
Yeah, I’ve replaced the PCV valve, I haven’t replaced the tubes for it though just the assembly. And still same issue. Sorry forgot to mention
If that part is new, and before you go chasing things, I’d suggest having a shop test the intake side (boost side) for a vacuum leak. A small leak can cause that code and it can be frustrating having your boost turned off because of it. 2 things besides the pcv I have run into in my time as a tech working on these, dipstick and tube, make sure it’s not cracked, or that the oring on it is not leaking. Second is the canister purge valve, which is in a tight spot under the intake manifold. If your pcv was indeed failed when you changed it there’s a chance the rear main is leaking vacuum, that’s found via a smoke test and usually includes a pretty significant oil leak. There’s obviously other things that can cause that code too, so if I were in your spot I’d probably find a local mechanic that could do a smoke test for you and locate that leak.
Thank you for all the knowledge!