Sorry, thought someone would reply.

I cant look at the PDFs, but some thoughts....

If something is off with the Air/Fuel mixture (aka AFR) then you can have a VERY rich mixture. (How is the exhaust around the tailpipes? Black and sooty, speckles?). This will cause the cats to be overwhelmed- and the DME will see the pre and post cat O2 readings and declare ‘the cat is bad’.

IN FACT, (and this especially true with the S62s) there were a TON of cats that BMW replaced under the federal warranty that were fine. Issues were sluggish vanes actuators And or intake air leaks leading to rich Running.

Also, when the AFR is whacked, you will get misfires. Too rich OR too lean, it will misfire. Now, many say that the DME should adjust, and once it hits the end of the adjustment you will get a rich or lean code. Not always. If a car runs off on AFR but only for PART of the rpm map, it may never get to a limit. A classic is “runs fine around town, but once I take it on the highway it trips. A code after 100 miles”. Around town you are seeing the full rpm range, on the highway it is basically at idle+..

Are you reading the full BMW codes? Or is that a generic reader??

Also, you will want to be able to live stream stuff like long and short term fuel trims. I think that may help.

I really (really) suggest you carefully inspect every hose and fitting on AND UNDER the intake plenum. Doesn’t take much of a leak to whack out the balance.

Pls confirm it is a 6cyl gasser too.

There is some odd crap that can happen with the valvetrionic control actuator, wonder if that is involved

Anyway, a few thoughts. Hopefully someone else chimes in. Oh, you know about www.newtis.info? Its like water...us fishes forget we are swimming in it. Figured I’d mention it.