Originally Posted by Chloe
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.
The secondary air injection system comprises the combination valve, which sits on the rear of the cylinder head in the 1.8T, hoses, and the pump itself. In a very common failure mode, the valve allows moisture to flow into the pump, which must then be replaced. I don't know about your state, but under California's emission system warranty laws, VWoA must cover the pump, but not the valve, for 7 years.