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I've got an 2012 A5 B8.

Sorry for the long post!

TL;DR 02/CAT sensors will not ready even after replacement and 5k miles driven, AUDI says last thing to do is replace ECU for boat loads of money. Looking for advice on if there is an alternate way to get the sensors to ready.

I bought it around 2018 with 65k miles and it's around 80k miles now.
Bought with a known turbo issue, which has been replaced with an OEM B&W K03. (not throwing anymore turbo codes)
It also had a slipping clutch that I didn't know about that got replaced twice (thought a new clutch/resurfaced flywheel would do it but it did not so it's got a brand new stage 1 clutch/flywheel).
spark plugs and coils have been replaced.
All non OEM parts aside form the clutch and cold air intake have been put back to stock.

I put in a CATless downpipe and used an O2 fouler to keep it from coding all the time but once I put the CAT back in for emissions testing the O2 and CAT have not readied since.

It's been to a high end euro repair shop that I get all my work done at and they could not figure out the issue so I took it to the AUDI dealership and they just replaced both my O2 and CAT sensors but after driving over 200 miles the Sensors still would not set.

AUDI told me the last option here is to replace the ECU for anywhere between 3k-5k$ which I think is just ridiculous but they could be right since I haven't seen the sensors set since the CATless downpipe which was removed over 5k miles ago.

I work in IT and know how screwy computers can be at times but usually there is a way to reset them to factory to fix a multitude of errors.

My question here is: Does anyone know of a way to get these sensors to set without replacing the ECU or would it just be better to bite the bullet and get it replaced at this point?

It is also fair to note that I have a massive cold start misfire at the moment and am unsure if the O2/CAT would even set with a permanent CEL on.

Any help here would be greatly appreciated since I have to either park it permanently or fix it by Feb. of next year (CA smog waivered currently about to expire).

Thanks again.
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