It's correct that a bad PCM can throw out a lot of odd codes -especially the o2 sensor and the EGR valve. I had similar code errors and replaced the o2 sensor and EGR valve--not difficult but kinda spendy--cleared the codes--and then got the exact same errors. Of course it was the PCM. If you consider what the PCM does it does make sence why it would throw off codes. Because it is true that an error code doesn't mean replace the part--just check it out. Good luck!!!