Code PO411, secondary air injection system incorrect flow
My 2001 Passat with 45,000 has the CEL on. I checked and the fault code is PO411, indicating there is an incorrect flow with the secondary air injection system. The CEL was consistently coming on until the weather turned cooler, but now it's on again. A couple of times I've thought I've smelled something, like burning, under hood when I shut engine off (yikes) but upon checking, I don't see anything. Any ideas? Could this be a vacuum hose problem? Thanks.