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Engine Code P0101 Solved


Veteran Member
Dec 16, 2011
2006 Jetta BRM with 200K
This code can be a nightmare to find. For me it was in time and money. Since it is specific to the MAF sensor, it can only be so many things. At the end of the day, it was a small vacuum leak in the lower air intake hose beneath the MAF sensor, a flex hose, that is prone to problems with age. The upper hose that has the MAF was fine.

The lower part ($150) is 3C0-129-565-B. This is actually a long plastic tube in one section and a short flexible part. It is the flex part that commonly gets a leak from a small hole (as in my case) that triggered the P0101 code. The name is Intake air tubing for use in cold weather countries.

The title forces me to ask: what does it do? does my car still need it even if I am in California? The car was originally in Colorado, which is way colder. If I do not need it, can I remove it and block off the connection ends?


Veteran Member
Oct 18, 2010
MkV Jetta BRM
When your intake air is cold it allows heated air from around the exhaust manifold to enter the air filter box. Once your air intake box reaches sufficient temperature whether due to the engine compartment warming up or warm enough intake air a little bi-metal thermostat spring expands in your air box to close off the heated air.

When you pull your air filter out you see this little springy door guy sitting there, at the other end of your new flex hose.

So even if you get rid of the hose you still need to block off the springy door in your air box. I don't know how cold it gets where you live but my suggestion would be to keep it, it'll help your engine warm up to operating temp sooner. (better mpg & better engine life)