Problem with my S4
 

Bought the car used few days ago at a used car dealership. When I test drove it the first day, I didn't noticed any CEL lights. After I got the car home and drove it around for an hour or so, CEL lights came on. During the drive, I noticed some sort of jerk/knock/misfire at full throttle or high rpm. Also noticed jerk/knock/misfire when shift from WOT 2nd to 3rd gear, I have tiptronic btw. It feels like shifting gear is not in sync as it jerks a couple seconds after I change gear. Anyway, got on the freeway and got up to 5th gear going about 70mph. The car feels like its hitting a limiter at 4k rpm and sometimes jerk then accelerate then automatically switch between 4th and 5th. CEL lights came on few mins later, codes are P0140, P1114 and P1118.

Something to do with O2 sensor no activity and internal resistance too high. Other than that, the car runs and shift fine at cruising speed, only when I punch the gas when this happens. Any idea? Thanks, I'm heading to a local mechanic to check this out, they're specialized in Audi, hopefully wont cost more that $400.

So I'm looking at either turbo leak, bad ECU, bad ignition coil plugs, bad O2 sensor, knock sensor? What else can it be and which can be eliminated just by looking at the those three codes.

BTW, love the car!

My first thought is, you bought it at a dealer so take it back to that dealer and complain about it. It obviously has an issue and they should fix it. Why take it to a mechanic and pay to have it fixed if you can get them to fix it for free?

Yeah don't take that crap, a lot of shady dealers just clear the SES light when the go to sell the car, then it comes on after you already test drove it.

Yup. Go back to dealer and demand satisfaction. Sounds like a shady dealer. Sorry to hear.