My friends a4 is throwing a p0411 code, the engine sounds terrible when you rev it, and it wont idle on its own at all, ive changed as many of the 5/32 vacuum hoses as I could get to, but the problem still persists. It is bad enough to make the car completely undriveable which ive never heard of this code doing and really need to get this problem fixed, does anyone have any ideas? ive gone through the haynes manual and the fsm and cant find a decent diagnostic process to figure out if its just a leak, one of the pumps died, or what...

 

have you checked the spark plugs? that code is for the secondary air injection meaning that you need a new air pump. also you might want to change the coolant temp sensor as it's been known to cause weird things to happen on the 2.8. you'll want to clean the throttle body too

 

P0411-Sec.Air Inj.Sys. Incorrect Flow Detected

Sounds like you have other issues as well as this -usually- does not cause idle issues. Are there any other codes? Have you adapted the throttle body?

Take your Haynes manual and put it next to the toilet. Somebody will eventually get good use out of it... as toilet paper. Bentley repair manuals are the only useable ones for Audi/VW.

 

well by the time i got to the car the battery was completely dead and it was throwing a bunch of codes that seemed to be related to improper voltage so i cleared everything out and now its just showing the p0411 code after keeping it running for a while and correct if im wrong here but if it was a misfire issue wouldnt i get a blinking MIL?

-edit, there are no pending codes either

 

You'll get the flashing light during the actual misfiring. Once it stops you'll have the light solidly on and can scan for logged codes to see which cylinders were to blame.

 

yeah well its not throwing a code for anything else, and at no point did i see the MIL blink, so i dont think its a misfire issue... any other ideas?

 

MIL will blink during misfires potentially casing damage to the catalytic converter, however it is very possible to have a misfire with a steady MIL. Since the battery died, I'd recommend charging or replacing the battery and then trying to adapt the throttle body.

 

the battery was replaced with a brand new one, and what exactly do you mean by adapt the throttle body?

 

Put the key in the ignition and turn on without starting car. Do not touch the pedals, leave in this position for 30 seconds. Turn off, then start the car.