B6 s4 fault code

[durrmcdanks]

My 04 s4 is throwing 16815 fault code involving a upper thermal bank problem. I was wondering if this was caused by the cat or the oxygen sensor. Does this hinder performance too and is there away around by getting a new sensor or straight piping and getting o2 sensor spacers? Please help thank you

[s4for5]

That code is for either of the 2 Oxygen sensors (front of Cat or rear) or the Cat itself.
Diagnostic procedures say to test each sensor first, then once the sensors verify they are used to test the Cats.
Failed sensors or clogged Cats can adversly effect performance.
I would not neglect this issue.