If you go back to the third post, you'll find the easiest and least expensive
test. VACUUM LEAK

 

Ok so I got the SAME code AGAIN - p0174 System too lean bank 2. Took about 3 weeks to show up again. No vacuum leaks anymore (all fixed) so that's ruled out, no drivability problems. Only thing I noticed is that thecar is much louder now and there is a backfire when deacelerating. Could itbe a problem with theexhaust?

 

the 12v cars will always backfire.

i have the same code. i cant figure out what is trigering it. it has been plaging me for a few monts now. all vaclines were changed not to long ago, a/f gauge is reading right before rich to rich, replaced both front o2 and have to replace one rear o2. still get bank 2 lean . on the dyno i am a bit lean side but not badon idle but as soon as i am moving it goes to normal.

any help

 

as an admin you would think so

also i would for the guy that brought this thread back from the dead, what i do when i can't figure it out, with vag or a scanner is go to dealer have them find the cause and fix it myself

 

it is probably not the MAF, or else both sides would be running lean. Make 100% sure all the vacuum lines are replaced or checked and check the pcv valve as well.
I'm betting it's the exhaust maifold gasket on that bank 2 side of the engine. it would explain the car getting louder too.
If not that, it could be clogged/dirty injectors on that side of the engine - the techron injector cleaner will only help so much....
Does the 2.8 have a different O2 sensor for each side of the engine? I really only have worked on the 1.8Ts.