2008 porsche cayenne turbo engine problems

[mmctinc]

Hi all, I am new to the forum and just picked up a cheap cayenne turbo with engine noises and engine codes P0431 warm up catalist efficiency below threashold.
P1346 ignition amplifier primary circuit 3 short to b+.
P1347 sensor 2, bank 2, ckp sensor improper sequence, I'm hoping its just a timing chain tensioner and not all the cylinder scoring that I've been reading about! anyone have any ideas or experience with cayenne engine noise and this codes combo