Air intake install goofs


New member
Oregon, USA
2008 MK5 GTI
Hey there, I've had my 2008 mk5 GTI (tsi engine) for about 7 months now and have been studying up on mechanics, and finally decided to do my first mod with a buddy. We installed a CX Racing cold air intake into my baby 2 days ago and it feels fine so far, but I have noticed a couple concerning things that need addressing. For starters, when we disconnected the stock air box we pulled out a big hose in the front and an attached sensor that I believe is the MAP sensor? And that threw a code I was told I could just clear, as well as the PCV return hose disconnected further back. The MAF sensor is plugged into a special housing that was part of the new pipe a little further back, thanks to some creative wiring. My problem is that there's now just a random wire harness (MAP? I think) and PCV hose floating in my engine bay and I don't like that one bit. I've seen stuff about breather hose kits I could put on the PCV hose or just slap on a catch can, but I'm not sure which one to do. We also spent like 2 days messing with hoses trying to find the right vacuum tube to install a boost gauge before we just gave up lol. In addition, when the engine feels like its making boost now it gives off a tiny, high-pitched whine. According to my research this is a DV issue and I need to order a new one. So I have a couple things I need to do, but the problem now is I'm trying to save money for a move right now and want to fix this as cheaply as possible. As of now it's throwing a check engine light for the air intake system that I have to go to a shop to reset (my buddy's code scanner wasnt able to clear it), and I still have that loose maybe-MAP wire harness and pcv return hose floating as well as a light whine that could be either DV or a boost leak from our hose-splicing boost gauge misadventures. Attached are pics of the disconnected stuff, pls let me know what I should do next. Thank you!!

Update: Took it to an auto parts store who suggested I put a filter over the pcv return line or cap it off entirely, said most air intakes would have a port for this but the one I got is a cheap chinese piece of garbage so oh well. I plugged in a couple sensors that were undone down where we pulled the big hose out with the air box, and got all the codes cleared though they should probably show up again. I also bent the return line up and away so it wouldn't drip over my turbo but now I can't get the engine cover back on. My friend says it'll be fine for now but I'm going on a road trip soon and need my car to not fall apart on me halfway to Montana. Other than that loose pcv return hose, the high pitched whine is continuing at higher rpms and my fuel mileage indicator is now somewhat lower than usual, giving me an indication of 295 miles for a full tank instead of the usual 330 or so. Please let me know any suggestions you might have.


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