P2198 code
 

FWIW, don't assume folks walk around ready to talk five character codes memorized in their heads. Thus, spell out what the code is. If it is a simplistic OBDII reader, you may need to look it up--rather than have us each do it. You will get more and better answers that way. Also, searching on the code with the word Audi and/or for models that use the same motor can often give you some decent leads.

Ok I finally got the image to load the 2 fault codes are p2098 bank2 sensor 2 too lean and p2198 bank2 sensor 1 too rich

What year and engine? Makes a difference.

2011 4.2l

When was your last tune up--plugs and air filter?

I have the same engine and year. Ran into the same problem at 90K miles and researched it to death. I have several friends who are Audi/Porsche techs that I can lean on for advice. Everyone said O2 sensors are rarely the problem and hard to properly diagnosis as a fault. This code is very generic and can mean many things as the pre-cat and post cat sensors are reading out of spec. The dealer maintained from the start it was the high pressure fuel pumps based on prior experience. I wanted to rule out potential items that I would have done anyway. Changed oil separator, plugs and filter first go around. No change.
Noticed an increasing sulfur smell from tail pipe and both banks ultimately read the same errors. I finally gave in and spent the big bucks to change out high pressure pumps even though the car ran fine except for the codes. I should have done the pumps myself to save a lot of cash). Problems went away but in the run up to solving the problem I ruined the cats filling them with too much raw fuel when running too rich.
Over time the cats cleared out and things are back to normal. I've read other people with the same problem on the 2011-2012 - 4.2's
Hope this helps. It's all I know!

Unfortunately, no.

While I don't recognize the issue personally, this reply makes sense to me. Per my earlier question, it was recently tuned up so that is eliminated. Running rich is rare; lean is the norm and most commonly a variety of vacuum leaks, or sometimes fuel starvation. Also the two sensors in tandem reporting pre and post cat with essentially opposite conclusions suggest to me this is probably not a sensor failure, but something in the fuel system itself. Many true sensor issues also have specific electrical codes that basically tell you it is physical wiring or a burned out sensor heating element. None of that is the case here--not seen in the codes. Pre cat (B2S1) reading is rich, while post cat it is lean, which tells me so far the cat is working hard and scrubbing the exhaust (for now...). The codes are also both bank 2, meaning the same side of motor--U.S./continental Europe driver's side. Suggests issue is thus on that side. Since car has a high pressure fuel pump (HPFP) on each side/bank, another possible confirming clue. Then within fuel you would be down logically to injector leakage or other issues or an HPFP issue. If it were an injector (or HPFP) running lean, you might have ignition misfire codes too, but for rich those are unlikely.

As a practical matter, an HPFP costs on the order of $400 parts wise--not sure about dealer price but a quick indy parts check got me to that #, which resonates true with a VW HPFP I bought. Easy typically to change out--very accessible on top of valve cover area. If dealer pokes at it very long, in the real world diagnostic labor bill will add up to the parts cost before even getting to the fix. Can't be definitive on this--especially arm chair--but one of those where practicality may say reasonable answer/educated guess is to change it out.

Update: the dealer did end up replacing the HPFP on the driver side got the car back drove it maybe 100 miles and the code is back. Dropping it off tomorrow morning

Have a 2012 S5 with very similar issues, P2098 and P2198. Replaced O2 which lasted 200 miles before the error returned. Was wondering if yaya ever found a fix?

Troubleshooting update: Too clarify previous post, 200 miles ago (aprox a month ago) I replaced Bank 2, Pre Cat O2 to clear the Too Rich error P2198.
Last night 2/11/20 I swapped both, pre and post Cat, O2's from left to right. I want to see if the error follows the O2 sensors or remains on the drivers side. While making the change I did notice the Pre Bank2 sensor plug was not fully seated, "locked in place". After moving it to the passenger side, Still had the issue of not completing locking down. So I secured the connectors with a tie wrap. Fingers crossed the unseated connector was the reason for the P2198 P2098 returning, (unseated meaning-still connected just not fully pushed together and locked). Reset code and will report if the error returns.

Update: One month later and the error has not returned (sound of knocking on wood). Hopefully the issue was the connector.