After years of trouble free driving and loving my big black beauty, my 40 valve 00 facelift A8 is getting on my bad side.

I have been unable to pass the NYS inspection for emissions reasons despite the things I have done.

It started with an O2 sensor (B2-S2), then replaced another one (B2-S1)... now it gets a rough idle, the CEL flashes for a few seconds and the VAGCOM is telling me bank 1 and bank 2 are both lean.

Just for fun I pulled all of the spark plugs (NGK iridium only 12k on them) on bank 2 and they were very white. This making the lean status true. Any ideas on what to do so I no longer come up lean?

If not I'm sticking my large black hunk of aluminum for sale on the side of the road. Anyone want it?

 

How many miles on the car?
Did running lean start immediately after O2 sensor change? Possibly dislodged something during replacement.
Check all vacuum lines...esp big ones.
No MAF codes?
Maybe fuel pump starting to go (common at high mileage)...or less likely, clogged fuel filter (not common).
Just a couple of guesses(?)

 

166k miles.
The codes are 17544 and 17546 both say fuel trim bank (1 and 2) system too lean
I was thinking it could be a vacuum leak or MAF so I cleaned the MAF sensor.
I'll have to check for vac leaks in the morning.

I've noticed on the top of the motor in the center at the back of the intake manifold is a large plastic dish that suck a ton of air. If I place my hand anywhere near it it sucks in and starts to stall the engine. What the heck is that thing?

 

"Mine is the art of fighting without fighting."

But seriously, I agree that it is most likely a vacuum leak. Shoot me a PM with your price if you want to sell. I may have an interested party.

l8r)