You might have the chicken or the egg deal here ..... misfires could throw O2 codes instead of bad O2's causing the misfire ... just and FYI.

 

my car is running off 4 generic o2's and 2 of them are cut and spliced! previous owner halfed *** a lot of stuff on this car.. it "WAS" running good/decent the first 8 months that i owned it and now its all catching up to me. im just gonna start replacing everything i can myself 1 piece at a time until its up and running the way it should be! thank you guys for all your help

 

Cut and splice!!! shoot that person that did that..

 

bump once again. i got all the o2 codes cleared and fixed now my car is only throwing 3 codes left! these are the remaining problems on my boxster... for some reason cylinder 2 stopped misfiring and only 1 and 3 is left. ive been searching around and i cant find much on resolving the problem but only others having the same issue. anymore knowledge you guys can teach me on how to fix this? thanks everyone!

misfiring problems :
P0300 Misfire Damaging to Catalytic Converter
P0301 Misfire, Cylinder 1, Damaging to Catalytic Converter
P0303 Misfire, Cylinder 3, Damaging to Catalytic Converter