My g/f drives an 02' A4 Quatro and the check engine light came on a couple days ago. I plugged in my CEL code scanner and came up with the following:

P171 - System too lean
P411 - Secondary Air Injection Ststem Incorrect Flow

I read your FAQ and it suggests: VAC Leak, MAF, O2 Sensor, Fuel Filter which I will start investigating tonight.

I'm more concerned with the second error, any suggestions?

 

from another post:

Check the hoses around your secondary air pump. it sits below the airbox. Usually the hoses get brittle over time and crack, and not enough air gets pumped into the back of the head.

If you search from the main a4 page for p0411, it'll give you a bunch of posts. The secondary air pump is used on cold starts to help heat up the cat, then shuts off. You probably have a cracked or loose or fallen off hose somewhere.

 

Great, so now I know where to start. I have no idea how to get around these foreign engines Where can I find a book on this car? I think autozone only sells em for domestic, right?

 

bently manual, about 80 bux

ebay has em

 

80 bux, are you serious! mother of god, I hope it's hardbound with gold lettering.

 

Go to any auto parts store, buy a haynes manual for it.

Not quite as good as bently, almost, I have one and it has never let me down. $15 for it.

But, remove your airbox and look for bad lines to the pump.

If you can't figure out where the airbox is, maybe you should take it somewhere to have it worked on.

Just kidding, so dont take my comment too seriously, unless its true!

 

Check for vacuum leaks in the vacuum hoses that supply vacuum going to the combi valves.

 

i had the same problem, look at the top of the intake manifold. there is a vacuum hose about 5-6 inches long. mine was pretty destroyed. fixed the problem for less then a dollar.