If you have a 1.8T, the breather for the crankcase is below the intake manifold. The poor design of the engine causes oil to be sucked up through the breather and sit in the breather assembly then causing it to rot and fail. When you aredriving slow, the vapors from your crankcase waft in through the cabin air intake. you need to purchase a breather T fitting, it is expensive -about 45 dollars from the dealer, and install it. Look below the intake on the drivers side of the engine for the faulty part.