Hi guys.

I drive a 2002 Audi A4 1.8t Quattro 5 speed. 94k

I recently had a check engine light flick on due to the error codes P0171 (Bank one too lean) and P0411 (Secondary air pump insufficient air flow detected). I checked all the hoses and found a small hose connected to the manifold that had deteriorated and also a check valve that was corroded. I replaced the two parts and disconnected the battery to reset the check engine light. The light stayed off for about 160 miles but returned as I was driving to get a state inspection done .

Does anyone know why these two codes would pop up simultaneously?

 

I recently had the P0411 code on my 2.8 30V and tried to inspect the small vacuum lines and decide which needed to be replaced. I found a couple but after I replaced them, wound up with the P0411 code again plus two other codes! I ended up replacing all the small vacuum hoses and that appears to have fixed the problem. Moral of the story is: it's really hard to tell for sure if one of those small vacuum hoses is bad or not so it's better and not that difficult to just replace them all.

 

I had the exact same problem bro, had to do a boost leak check which I found a good tutorial on a4mode.com, turned out to just be a cracked hose, fixed both error codes after replacing

 

I've
Replaced a few pipes but I haven't been able to get the codes cleared yet. I think Auto Zone can do otnd