Have you ever had the car walnut blasted to clean the back of the valves since it’s a direct injection motor. Carbon build up cause all kinds of issues that have lead many on wild goose chases looking for other issues.
I have the same code reader it works well. If you have an exhaust leak that is where your problem probably is. Dave is right carbon is a problem on the N14 engine. Its more of a problem on the S, but you may want to check the intake to make sure its clean.
The non-turbo N12 motor doesn't have direct injection, it has port injection so, the intake valves are continuously washed by the injectors. No carbon build up problems on the N12 engine.
Oh my bad, n12 then? All I know is it don't have a turbo/supercharger, it was late too. Thanks for the tip!